Started work on a simple OAI-PMH provider.

Started work on a OAI-PMH provider which can be used for testing OAI-PMH
harvesters.
Added support for ListSets and Identify
Added ListIdentifier with resumptionToken (but not dates)
Added support for ListRecords
Add GetRecord implementation.

Added the implementation for the GetRecord verb in the 'serve' command.
Started work on a search command.

This command will harvest from the OAI-PMH provider, and will list
metadata records which match a specific XPATH expression.
Started work on removing gokogiri.

Started work on removing gokogiri.  Will be replacing it with Go's
builtin XML utilities.
Refactored the remaining calls.

Refactored the remaining calls and removed gonokowi as a dependency in
oaipmh-parser.
Added target for Windows.

Added a target for Windows using Go's cross compiling capabilites.  Have
also fixed a bug with loading of the users config file.
Improved search predicates.

Added proper search predicates which can return values.  Started work on
the 'xp()' predicate which runs XPath expressions.  This makes use of
'launchpad.net/xmlpath' which, hopefully, is cross platform.
Moved the mapreduce file into a separate module.

Also changed the code slightly to make better use of Go channel
primitives.