[fix #52699413] Added UpdateLabellable action
bump version to 1.7.0
fixed the root json spec
Added a validation for update labels information
removed duplicated action after merge
Added rake for gemspec for Travis build
[fix 52699413] removed the possibility adding new labels
removed update method from labellable_sequel_persistor
[fix #52699413] Added UpdateLabel action

and removed UpdateLabellable action.
inherit parameter related errors from InvalidParameters

also refactored the action execution code
changed the error message for insufficient information
added more tests for invalid parameters
Merge pull request #39 from ke4/52699413_add_update_action_for_labellable_resource

52699413 add update action for label resource