Added CHANGELOGS of version 0.8.0

CHANGELOG.md

 # Changelog of pygeodyn
 
+0.8.0
+-----
+Numerous improvements in view of future release:
+* Renamed the project in **pygeodyn**
+* Switch to semantic versioning
+
+In addition :
+* Added continous release tools (not used for now), CHANGELOG, version handling
+* Clean-up of fortran source files
+* Removed deprecated files
+* Added benchmarks files for functional tests of the algorithm (only implemented for regular AugKF)
+
 0.7
 ---
 New features: