Moved extensions_test to extensions/base_test

For expanding the extensions area.
Added shared_context helper to test cases

Shoulda doesn't appear to give something handy-dandy for sharing
test snippets.  If the test subject is amenable to solely assembling
chains of setup blocks, that's great, but that's not the case I
have.  Furthermore, you want to be able to reuse the various assertions
readily.

Maybe I'm missing something obvious, but here we are.

Added a :shared_context singleton method to Test::Unit::TestCase
that lets you define other singleton methods using blocks.  The
methods, when called, are evaluated in the current shoulda context,
meaning they can have arbitrary setup/should/etc. blocks within.

This can make tests with a lot of redundant checks DRY and declarative.
Hadupils::Extensions::Hive

Class for assembling hive initialization and auxiliary jar info
based on layouts within filesystem.
Hadupils::Extensions::HiveSet implementation

The HiveSet allows a directory to act as a collection of
Hadupils::Extensions::Hive subdirectories, and provides a
convenient interface for aggregating all jars and initialization
files and whatnot across the collection.

Also added a hive_aux_jars_path method to the Hive (and HiveSet)
classes to make it easy to use in preparing calls to hive.
Added hive extensions lookup to Hadupils::Search

Find "hive-ext" directory from pwd with the exciting, new
Hadupils::Search.hive_extensions singleton method!

Impress your friends.  Earn the respect of your peers.
Dominate your loved ones.
Hive runner/command support HIVE_AUX_JARS_PATH

The hive runner and command need to be able to support the
specification of HIVE_AUX_JARS_PATH in the underlying hive
environment at call time, based on hive extension information.

This nastiness involved:
* Adding support to the command runner to detect the case where the
  first parameter to be executed and handle it special (for pre
  ruby-1.9)
* Adding support to the runner for inclusion of the hive auxiliary
  jars into the mix (as HIVE_AUX_JARS_PATH environment variable)
* Various tests that mess with globals like ::ENV and ::RUBY_VERSION.

Fortunately, this all means that if you have hive extensions
following established conventions, their auxiliary jars should be
in place within the environment variable.
Merge branch 'hive-ext'
Bump to version 0.2.0