Fix gallery link option

Galleries should support three link types:

* Attachment Page (default): [gallery ids="1,2,3"]
* Media File: [gallery link="file" ids="1,2,3"]
* None: [gallery link="none" ids="1,2,3"]
Add analytics
Ignore LESS source map
Match wp_register_script function signature

Although the third parameter currently works when false to indicate
no dependancies, it works by side-effect, the function signature uses
an empty array to indicate no dependancies.
Merge pull request #956 from roscius/register_script

Match wp_register_script function signature
Merge pull request #947 from leoj3n/gallery-fix

Fix gallery link option
Ignore LESS source map