Fixes issue #478. This level of detail is excessive as a default.

This commit adds the Data Science Toolkit as a lookup type.  The DSTK behaves identically to the Google Maps API with the exception that it can be run behind your own firewall.  More information about this tool can be found here: http://www.datasciencetoolkit.org/

Addresses issue #450. Wish we had sample response to see exactly what
data was returned, but we don't.

This was causing unintended resuce from other exceptions like:
Errno::ECONNREFUSED: Connection refused - Unable to connect to Redis...

rack/utils is not a dependency and therefore cannot be required.

This was causing an exception when `join` was called on the resulting
string.

instead of inferring from response length. This is less than ideal but
it fixes issue #396 and, given what appears to be MaxMind's inconsistent
response lengths, it may not be possible to do much better.

In addition to checking for []/[]= and set/get, also check
for functions like read/write.

fix regexp match in yahoo lookup to use xml boundary instead of newlines. fixes broken lookup unit test

Geocoder::Lookup "cache" method now public; Geocoder.cache method calls cache method instead of configuration key.

Ideally, datenimperator-add-ovi would have been rebased to master before
being merged.

Use \A and \z in regular expressions to avoid newline issues. Also, do not consider any address that begins with 127 to be a loopback IP.