Require HTTP basic auth for github webhook

Previously, we only checked that X-Forwarded-For (set by Heroku)
contained an IP from a trusted range. However, GitHub recommends
HTTP basic auth:

https://help.github.com/articles/what-ip-addresses-does-github-use-that-i-should-whitelist
Merge pull request #18 from fxkr/require-http-basic-auth

Require HTTP basic auth for github webhook
Expand repository definition to support FREEBIE/MONEYMONEY default.

Repositories can either be defined to have a mode of
'MONEYMONEY' (default), where every commit is paid out on unless
it contains the tag 'FREEBIE', or can be defined to have a mode
of 'FREEBIE', where commits aren't paid out unless they contain
the tag 'MONEYMONEY'.
Remove unused import //FREEBIE
Add website index page

For now it only contains a backlink to the GitHub project.

* Since Dropwizard can't serve both the service and the static assets
  from the root path[1], we move the service to /service/. Existing
  clients (e.g. the Github webhook) will need to be pointed to the new
  location. Note that this could have been avoided by either:

    a) moving to /v1/ instead, but that would preclude a /v2/, or
    b) rewriting the URL with a filter like in [2]

* Pulls in Bootstrap from bootstrapcdn and jQuery from code.jquery.com.
  That way we don't have to copy them into our repo. It might be seen
  as a privacy problem though.

[1] http://dropwizard.codahale.com/manual/core/#serving-assets
[2] http://stackoverflow.com/questions/20076495/
Add information to index page

- explanation how BitHub works
- reward for next commit
- donation button (if code is set in config)
- list of qualifying projects

//FREEBIE