Add info on why WOFF files shouldn't be compressed

Ref: h5bp/server-configs-apache#42
Add data for WOFF 2.0 font files

Ref: http://dev.w3.org/webfonts/WOFF2/spec/#IMT
     h5bp/server-configs-apache#32
Add data for WebVTT files (`.vtt`)

Mark WebVTT files as:

 * having the default charset `UTF-8`:

   "A WebVTT file must consist of a WebVTT file body encoded as UTF-8"

   (from http://dev.w3.org/html5/webvtt/#h2_syntax)

 * compressible - they are text files, therefore, they compress
   quite nicely, also, clients that have support for WebVTT shouldn't
   encounter any problems when the `.vtt` files are being served
   compressed (browsers at least, do not):

   "If WebVTT segments are distributed by HTTP, the server SHOULD
    support client requests to use the "gzip" Content-Encoding."

   (from http://tools.ietf.org/html/draft-pantos-http-live-streaming-13)
Add data for JSON-LD (`.jsonld`) files

Mark JSON-LD files as:

 * having the default charset `UTF-8`
 * compressible (they are basically text files, therefore, they compress
   quite nicely)

Ref:

  * http://json-ld.org/
  * http://www.w3.org/TR/json-ld/