clean up easyconfig unit tests
add unit test for exts_list
fix exts_list test
move resolve_template function outside of EasyConfig class, to make it accessible to others
use resolve_template function from easyconfig.py to resolve templates for extensions
fix import for easyconfig tests
Merge pull request #646 from boegel/fix_bugs

fix ext source_urls templating bug, rework easyconfig tests, refactor resolve_template function
Merge pull request #647 from boegel/fix_bugs

fix import for easyconfig tests
correctly specify whether sanity check should be done for an extension or not
Merge pull request #649 from boegel/fix_bugs

correctly specify whether sanity check should be done for an extension or not
update release notes, bump version to v1.5.0
fix typo
Merge pull request #650 from boegel/v1.5.x

update release notes, bump version to v1.5.0
bump version to v1.6.0dev
fix remark w.r.t. modulefile_path function, throw exception when module doesn't exist
Merge branch 'develop' into init_lmod