Added plugin scripts

Gen_JSON:

This script can create a json file from a folder of plugins. It reads
the plugin files to extract information such as Author and Title from
them, and creates a json with all that data. The json also contains the
MD5 hashes of all the files used.

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Plugin_API:

The json generated above is loaded and served as via Flask.

It supports the following endpoints:

/plugins   Lists details of all the plugins

/plugins?id=<plugid>  List details of a specific plugin

/download?id=<plugid>  Increments the download count and initiates
download of a plugin. If a plugin contains a single file, it is
served as is, whereas if there are  multiple files, they are zipped
together.
Improved the Gen JSON script and removed the API.

Better regexes are now used so the data does not contain characters that
'look' bad.

The Description field had to be given special attention as it is spread
out in multiple lines.

The API will be added again as a part of the main website itself.
Fixing issues raised in the comments

The file has been renamed to generate_json.

The regexes have been moved out of the function, so they are not
compiled every time the function is called.

The entries in the JSON have been renamed for better readability.
s/ver/version, s/apiver/api_version, s/desc/description.

The JSON now stores the plugins as a dictionary rather than a list, so
searching for plugins is simple.

All variables are noe camelCased.
Merge pull request #6 from musicbrainz/scripts

Added Generate JSON script.