Add license, update README wrt numpy performance issues

Author: lmcinnes

LICENSE

@@ -0,0 +1,12 @@
+Copyright (c) 2015, Leland McInnes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.rst

@@ -16,12 +16,6 @@ HDBSCAN is ideal for exploratory data analysis; it's a fast and robust
 algorithm that you can trust to return meaningful clusters (if there
 are any).
 
-**WARNING**: Numpy version 1.10.1 introduced `performance regressions in structured
-array access <https://github.com/numpy/numpy/issues/6467>`_ ; this does have
-a notable performance impact on hdbscan. Consider upgrading to a newer version,
-or downgrading in the meantime if performance counts. I will be working to
-ensure hdbscan performance regardless of this issue in coming releases.
-
 Based on the paper:
     R. Campello, D. Moulavi, and J. Sander, *Density-Based Clustering Based on
     Hierarchical Density Estimates*