Fix PC matrix calculation from CD matrix.

This fixes a bug with SWAP files.
Write some broken tests.
Fix CD matrix test and test file
fix database test numbers
Conflicts:
	sunpy/database/tests/test_tables.py
Change the travis matrix so that most of the build are offline.
Only do coverage on the online build.
Remove Python 2.6 from the travis build
Find Python 2.6 references and remove them
Merge pull request #1190 from Cadair/travis_flip

Change the travis matrix so that most of the build are offline.
Merge pull request #1188 from Cadair/cd_matrix_fix

Cd matrix fix
Add gitter notifications to Travis
Merge remote-tracking branch 'upstream/master' into rotate