Raise zero error code if TRAVIS_PULL_REQUEST is 'false'

Allow Travis build on individual branches to be successful
Merge pull request #77 from sbesson/travis_scc

Add support for scc merging in Travis
Split unit tests into individual lines

Some tests were failing but for some reasons the Travis status was returning
the last error code (and thus passing). This commit should allow any failing
test to exit the Travis build with a non-zero code.
Delegate error code and message to GithubException in get_github()
Update TestConfig unit tests to expect Stop Exception
Do not fail for anonymous connections
Remove anonymous failing test
Split repo filter tests from command argument tests
Refactor filter parsing unit tests
Test -Ddefault filter parsing
Add support for PR inclusion/exclusion using hash symbol

Allows to include/exclude PRs using `scc merge base -I#pr1 -E#pr2'
Fix travis-merge PR inclusion to read --depends-on #pr comments
merge master -D org -I include -E exclude: PR 78 (Travis test)
merge master -D org -I include -E exclude: PR 79 (Use hash symbol to include/exclude PRs)