bump version to v1.11.1, update release notes
Merge pull request #877 from boegel/assertErrorRegex

clean up assertErrorRegex copy-pasting in unit test modules via central EnhancedTestCase
Merge pull request #876 from boegel/v1.11.1_release

bump version to v1.11.1, update release notes
Merge branch 'v1.11.x' into develop

Conflicts:
	easybuild/tools/version.py
add BuildOptions class in tools/config.py + unit tests for it
flesh out DictObject, extend list of required configuration variables, initialize global VARIABLES through config.init() function
fix unit tests w.r.t. changes in tools.config module