Adding integration tests in support of the RAVEN superevent
field and VOEvent changes.

adding combined_skymap_filename (optional string)  and raven_coinc (optional boolean) to createVOEvent method

Update .gitlab-ci.yml: the default python3 version was changed in the ligo/base:el7 container, so the build dependencies had to be changed to reflect that. 

According to the classifiers in setup.py, Python 2.6 is no longer
supported by this package.

Add the ability to print the certificate's subject and expiration
date/time.  Add information on using these new functions to the
troubleshooting docs.  Add unit tests.

README.md file doesn't seem to come along for the ride when
system packages are built, so we converted to .rst format,
since that seems to work.

Hasn't been used on the production server since 2015, actual
usage was only very minimal. The model and related endpoints will
be removed from the server in the near future.

fixes #22

Add update_grbevent method to ligo.gracedb.rest.GraceDb. Used for
updating parameters of GRB events.

Required since 1.9.0 is what's run in EL7 and it seems to work fine.
We just used 1.10.0 as a way to fix the version at something
that seemed reasonable.

easy to resolve dependencies when building a src.rpm