Added a check for existence of wp_get_theme()

Adding a check for existence of wp_get_theme() to add support for
Wordpress versions older than 3.4.
Added a check for existence of wp_get_theme()

Added a check for existence of wp_get_theme() to allow theme to support
Wordpress versions older than 3.4.
Merge pull request #102 from scone/master

Fix issue #101 - Thanks @scone.