Work in progress on experimenting with the magnet pattern in order to properly allow all possible overrides of the store method

Looking good...
Found a better way to make default fallback (de)serializers available in implicit scope without direct imports
Created a default fallback NoopRiakIndexer
Seems like I could get away with avoiding the Magnet pattern one more time, since all of this compiles without problem and seems to test correctly too.

Many more tests needed of course...
Made sure the RiakIndexer type class default implementation has the absolute lowest possible precedence
Added indexes to RiakValue and RiakMeta, resulting in a nice refactoring that simplified the API even further

The only thing left to do is index header parsing and index header creation in HttpRiakClient
Added TODO for adding a setting for silently ignoring Riak backends that don't support indexes
Added some http header constants
Turned RiakIntIndex into RiakLongIndex because Riak stores values as 64-bit (unsigned) numbers
Cleaned up the HtpRiakclient imports a bit
Fixed a bug where RiakValue.toMeta didn't pass along its indexes
Removed old commented apply methods from RiakValue
Implemented HttpRiakClient support for secondary indexes, mapping to and from the relevant HTTP headers
Added some basic util traits for writing tests
WIP: First 4 unit tests for storing and retrieving with indexes
Extracted test data into separate TestData.scala file and got rid of most duplication in the indexer tests
Implemented proper escaping of commas in "bin" index values using URLEncoder/URLDecoder
Added lots of tests for the storing and retrieval of indexes
Added support for determining the full name of an index (i.e. including its suffix)
Fixed some invalid index values (i.e. removed spaces) because Riak doesn't accept url encoded spaces as valid values during a fetch