Return disposables from MenuManager which can be used to remove menus
:pencil: Update docs
:lipstick: spec description
Don’t add duplicate items to the same menu
Construct test instance of MenuManager in spec
Add split commands to editor context menu

Refs atom/tabs#85
Upgrade to tabs@0.54
Add --deep codesign option for 10.9.5
Use long options
Upgrade to language-coffee-script@0.35
Reorder config methods for easier digestion
Update ::observe and add ::onDidChange
Deprecate unused / unnecessary methods
Handle schema loading
Add type filter system to config
Support more types
Handle validation of schema types
Add an object filter
Support arrays
Handle bad values in number type