Core: Updates field_group from 1.2 to 1.3, contains feature support.

## Ready State: Yes

This update is important for features integration. The features version that abstracted fields into bases and instances required changes to field_group, which didn't land until 1.3.

## Requirements & Dependencies

* None

## Deployment Instructions

* Merge code.
* Rebuild module `field_group`: `drush make modules/imagex/modules/imagex_common_fields/drupal-org.make ./ --working-copy --no-gitinfofile --no-core --contrib-destination=./ --no-cache -y --projects=field_group`
* Update database: `drush updb`
* Clear caches with `drush cache-clear all`

## Usage/Test Instructions

* Export a feature with field_groups and install on a fresh site to ensure field groups are created properly