* auto creating release_notes and package_manifest

release_notes now provide links to individual
repository release notes instead of collecting them
together

Using anonymous access with github3.  Note that this
has API call restrictions, so can only do so many times
within an hour before being blocked.

setup.py install now runs the two scripts in source
to generate the manifest and release notes rst files.

minor changes to py scripts to use different org access
calls, and defining output path to not be CWD.

requirement and calls to pandoc have also been removed.
files are written directly to rst instead of being
written to md and converted.

* Exclude non-astroconda packages from release_notes

* change disclaimer at top of release notes