Add configs for JSON Schema files (`.json`)

* Ensure that files labeled with the `application/schema+json` media
  type are served compressed and are not cached.

* Since files containing JSON Schemas use the `.json` extension, they
  won't be served with any of the `HTML` document related headers and
  their specific character encoding will be `UTF-8`.

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Note: Because these types of files don't have their own specific file
extension and we can't know exactly if the `.json` file will contain a
JSON schema or just regular JSON, setting the media type (namely:
`application/schema+json`) will have to be done by the user, either by
configuring Apache (e.g.: https://github.com/h5bp/server-configs-apache/blob/58fb1d1b74cac4963d22ab018b77c80f595861fd/dist/.htaccess#L152-L174),
or from the level "beneath" the server (e.g.: from PHP).

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Thanks @fruitl00p!

Ref http://json-schema.org/latest/json-schema-core.html
    h5bp/server-configs-apache#39

Close h5bp/server-configs-apache#39
Make Travis CI limit the Git clone depth even more

In order to speed up the tests a little bit more, this commit informs
Travis CI to limit the Git clone depth to 10 commits (default is 50).

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e.g.:

 $ time g clone --depth 10 git@github.com:h5bp/server-configs-apache.git
 ...

 real    0m2.549s
 user    0m0.068s
 sys     0m0.048s

 $ time g clone --depth 50 git@github.com:h5bp/server-configs-apache.git
 ...

 real    0m3.139s
 user    0m0.128s
 sys     0m0.024s

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Ref: http://git-scm.com/docs/git-clone
     https://twitter.com/travisci/status/288390896339267584
Add configs for files marked as `text/javascript`

By default the configurations from this repository ensure that
`.js` files are served with the `application/javascript` media
type, compressed, and with far future expires headers. However,
not all users¹ use all the configurations provided by this
project, or, in some cases, the headers are overwritten from the
level "beneath" Apache (e.g.: from `php`).

For most of these cases we can't do anything about it.
Nonetheless, there is one, quite common case (the media type is
set to `text/javascript`) where we can help.

Since the `text/javascript` media type is used² quite often, this
commit makes Apache serve anything labeled with this media type,
compressed and with far future expires headers.

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¹ h5bp/server-configs-apache#27
  h5bp/server-configs-apache#41

² Even the Google CND serves `.js` files with the `text/javascript`
  media type (e.g.: http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js)
Update `CHANGELOG.md`
Fix link in `README.md`
Merge pull request #1 from h5bp/master

Update from original