Merge pull request #28 from greatislander/master

Add support for multi-select field with optional support for chosen.js. Fixes #9 and ref #12.

props @greatislander
Remove unnecessary debug method.
Remove bundled version of jquery-datepicker; using core version instead.
Add support for include/exclude callbacks.

Using slugs and ids are hard to sync across environments. It's more useful if we can programattically determine if a field or group should be included or excluded.
Update readme.md with new callback option for include/exclude.
Remove TODO list from code.

These are now tracked as issues here: https://github.com/jkudish/custom-metadata/issues
Introduce new actions: custom_metadata_manager_init and custom_metadata_manager_admin_init

These will allow for better integration with other plugins. It also removed the need for function_exists checks when registering fields/groups.
Update our code samples to use the new custom_metadata_manager_admin_init hook.

We can also remove the function_exists checks when registering fields/groups.
More new hooks: custom_metadata_manager_init_metadata.

This will allow users of the plugin to optimize their field/group registration only in the contexts where necessary instead of admin_init.

Update examples and docs as well.
No need to pass $this as a reference in callbacks.
jquery-ui-datepicker and chosen-js are dependencies for the custom metadata js.
Activate over-protective mode: escape all the things.
Use esc_textarea to escape the textarea
Introduce new filters to override arguments when registering fields/groups or when fetching various callbacks.

These are necessary for WordPress.com VIP so we can override various pieces like storing user data in "user attributes" instead of meta and enforce sanitization.
Translate some strings.
Bump working version number to 0.8-dev
Remove the variable version of custom_metadata_manager_init_metadata.

We can just pass the $object_type as an arg.
Convert to timestamp before sanitizing with a callback. Otherwise if a callback is set, convertion will never happen, resulting in a malformed value
Merge pull request #35 from rinatkhaziev/master

Make sure we convert datepicker to timestamp before calling callback to sanitize
Fixing checkboxes not being marked as checked