Fix exception creating key file under Python3

This should fix #55
Also, remove stale dependencies for Python 2.  Hey all, if you haven't
already, you may want to backup your octoprint settings (recent versions
have a feature for that) and make a new OctoPi 0.18 image for your pi.
It'll move you to Python 3 and give you a fresh OS too.

octoprint_polarcloud/__init__.py

@@ -302,26 +302,36 @@ def _system(self, command_line):
 			self._logger.exception("Failed to run system command: {}".format(command_line))
 			return (1, "")
 
-
-	def _get_keys(self):
-		data_folder = self.get_plugin_data_folder()
-		key_filename = os.path.join(data_folder, 'p3d_key')
-		self._logger.debug('key_filename: {}'.format(key_filename))
-		if not os.path.isfile(key_filename):
-			self._logger.debug('Generating key pair')
+	def _generate_key(self, key_filename):
+		try:
+			self._logger.info('Generating key pair')
 			key = crypto.PKey()
 			key.generate_key(crypto.TYPE_RSA, 2048)
-			with open(key_filename, 'w') as f:
+			with open(key_filename, 'wb') as f:
 				f.write(crypto.dump_privatekey(crypto.FILETYPE_PEM, key))
 			if sys.platform != 'win32':
 				os.chmod(key_filename, stat.S_IRUSR | stat.S_IWUSR)
+		except:
+			self._logger.exception("Unable to generate and save new private key")
+
+	def _get_keys(self, force_regen = False):
+		data_folder = self.get_plugin_data_folder()
+		key_filename = os.path.join(data_folder, 'p3d_key')
+		self._logger.debug('key_filename: {}'.format(key_filename))
+		if force_regen or not os.path.isfile(key_filename):
+			self._generate_key(key_filename)
 		try:
 			with open(key_filename) as f:
 				key = f.read()
+			if force_regen and len(key) <= 0:
+				self._logger.warn("Found zero length key, generating a new key")
+				self._generate_key(key_filename)
+				with open(key_filename) as f:
+					key = f.read()
 			self._key = crypto.load_privatekey(crypto.FILETYPE_PEM, key)
 		except:
 			self._key = None
-			self._logger.error("Unable to generate or access key.")
+			self._logger.exception("Unable to generate or access key.")
 			return
 
 		if hasattr(self._key, 'dump_publickey'):
@@ -795,6 +805,8 @@ def _on_register_response(self, response, *args, **kwargs):
 
 	def _register(self, email, pin):
 		self._get_keys()
+		if not self._key:
+			self._get_keys(True)
 		if not self._key:
 			self._logger.info("Can't register because unable to generate signing key")
 			self._plugin_manager.send_plugin_message(self._identifier, {

setup.py

@@ -4,7 +4,7 @@
 plugin_identifier = "polarcloud"
 plugin_package = "octoprint_polarcloud"
 plugin_name = "OctoPrint-PolarCloud"
-plugin_version = "1.12"
+plugin_version = "1.13"
 plugin_description = """Connects OctoPrint to the PolarCloud so you can easily monitor and control outside of your local network"""
 plugin_author = "Mark Walker"
 plugin_author_email = "markwal@hotmail.com"
@@ -61,15 +61,6 @@
 
 	if int(setuptools.__version__.split('.')[0]) < 40:
 		print("May not be able to successfully install with setuptools earlier than 40.0.0. If this fails, upgrade setup tools with 'pip install --upgrade setuptools'.")
-	else:
-		plat = distutils.util.get_platform().replace('.', '_').replace('-', '_')
-		if sys.version_info[0:2] == (2, 7) and plat in ['linux_armv7l', 'linux_armv6l'] and not hasattr(sys, 'pypy_version_info'):
-			plugin_requires = [
-				"cryptography @ https://markwal.github.io/wheelhouse/cryptography-3.0-cp27-none-" + plat + ".whl",
-				"cffi @ https://markwal.github.io/wheelhouse/cffi-1.12.1-cp27-none-" + plat + ".whl",
-				"Pillow @ https://markwal.github.io/wheelhouse/Pillow-5.4.1-cp27-none-" + plat + ".whl",
-			] + plugin_requires
-			add_pillow = False
 except:
 	import traceback
 	traceback.print_exc()