Remove ability to add new revision posts in admin
Merge branch 'issue-30' into develop

Closes #33
Closes #30
Merge branch 'master' into develop
Only update a setting if it has not changed

Use isEqual from Underscore.js to check if non-scalars are equal
Serialize all values (even strings) when saving settings

 * Serialization is needed to get around wp_slash() turning arrays of
   non-strings into strings, for example if a widget instance is saved
 * Refactor logic for parsing the postmeta key containing the setting id and type
 * Add a temp_customize_sanitize_js filter so that other plugins can have a chance
   to run serialization for the output JS-value (used by Widget Customizer)
 * Refactor to utilize get_revision_settings()