feat(Resource): add custom headers handling
docs(README): update the README.md
feat(Resource): add custom response transform/procesing
docs(README): update the README.md
chore(karma): add code coverage support to karma tests
fix(Resource): always use '$id' instead of 'id' field
feat(Resource): implement more robust URL handling
feat(Resource): handle query parameters and data for REST operations
fix(Resource): fix relations handling
fix(Resource): fix toObject behaviour for missing/null fields
test(Resource): add tests for .$save with relations
fix(Resource): align promise handling for collections to instances
fix(Resource): make minor fixes
chore(Gruntfile): add options to 'release' (version type and bump-only/commit-only)
chore(release): v0.3.0