Pygelbooru

Additions:
* Support for other Gelbooru compatible API's has been added via a new `api` parameter in the Gelbooru class. The API_RULE34 and API_SAFEBOORU constants have been added for convenience.

Fixes:
* has_comments and has_sample were returning incorrect values
* Custom loops are now properly utilized when supplied

Breaking changes:
* Gelbooru.tag_list() will now ALWAYS return a list of GelbooruTag

Breaking changes:
* **GelbooruImage.created_at will now return a datetime instance instead of a string**
* **GelbooruImage.changed will now return a datetime instance instead of an integer timestamp,**
* GelbooruImage.has_sample will now return a boolean instance of an integer,
* GelbooruImage.has_comments will now return a boolean instance of an integer,
* **GelbooruImage.has_notes will now return a boolean instance of a true/false string,**
* GelbooruTag.ambiguous will now return a boolean instance of an integer.
* **GelbooruComment.created_at will now return a datetime instance instead of a string.**
* GelbooruComment.post_id will now return an integer instead of a string
* GelbooruComment.creator_id will now return an integer instead of a string

New additions:
* The following new attributes have been added to GelbooruImage results:
- has_children
- status
- locked
- score

12 / 13 : Resolves errors caused by API schema changes on Gelbooru

Changes:
7: Resolves a potential KeyError on certain tag lookups

Changes:
1 : Add loop as an argument to __init__
2 : Removed hardcoded limit of 100 results
3 : Add support for a get_comments method
4 : Adds a random_post() method for fetching a random result