Added release step to check for Mend issues in internal repo

[andy-maier]

Some review points:

• I think that Mend only uses the requirements files from the master branch. That's why only the master branch gets synced.
• The new step has a link to the internal repo's issue tracker
• The commands in the new step use the "ibmfork" remote name.

Note that the wiki of the internal repo has instructions on how to set up the environment, including the "ibmfork" remote name.

[coveralls]

coverage: 77.588%. remained the same
when pulling 37b26f3 on andy/check-mend-during-releasing
into 1240cb0 on master.