rewrite internals and backends for better readabillity

This internal rewrite is based upon recommendations
documented in the joyent best practices guide.

In addition to this new functionality had been added to
support full multi-tenancy with multiple sites that are
meant to be monitored. Meaning: Should you have more than
one customer you wish to monitor you may configure
boomerang this way in the backend. Documentation for this
will be added in the near future.

Also a security enhancement has been made where uid and gid
can be set using master.json and configure your uid/gid
this way.

Useragents will be properly analysed now using the useragent
module from npm.
Update documentation and add logo for boomerang-express

An initial logo and icon have been added. Plus setup
documentation has been extended.