Lower PHP requirement to 5.6, deprecate modules

Removed

• the haveOrUpdateInDatabase method from WPDb module
• the ExtendedDb class
• the requirement of the lucatume/wp-snaphot-assertions package
• the \tad\WPBrowser\Snapshot\WPHtmlOutputDriver class
• the wpcept binaries
• lucatume/wp-snapshot-assertions dependency
• tad\WPBrowser\Snapshot\WPHtmlOutputDriver proxy class and the lucatume/wp-snapshot-assertions dependency
• wpcept and wpcept.bat deprecated binaries
• Codeception\Command\DbSnapshot command
• tad\Codeception\Command\SearchReplace command from the template
• lucatume/codeception-setup-local dependency
• the WPBootstrapper module
• the WPSugarMethods trait

Fixed

• compatibility with Codeception 2.5.0 updating the WPDb class
• added a clear disclaimer about db wiping in the init wpbrowser command
• an issue where the WpWebDriver module would not login correctly #121
• code style compatibilty with PSR-2 standard
• an issue in the tad\WPBrowser\Tests\Support\importDump function that would prevent the function from working if the database host specified a port
• an issue with end-of-line chars in tests on Windows #191 - thanks @Luc45

Changed

• lowered the PHP required version from 7.0 to 5.6
• PHP requirement lowered to PHP 5.6
• removed the limit to Codeception version
• Travis tests run now on a Docker stack

Added

• add a .gitattributes file to stop littering people's vendor library (sorry, my bad)
• support for relative paths in the wpRootFolder parameter
• the WPCLI and WordPress modules will now set the WPBROWSER_HOST_REQUEST=1 environment variable; this can be used to discern requests coming not only from wp-cli, using the WP_CLI constant, but from a wp-cli instance used and managed by the WPCLI module.