RUBY-570 removing test files from gemspec (for now)

The structure of our combined test suite doesn't allow it to be separated out easily so that it can be included with each gem in our repository (specifically, the test_helper).

Since you can't actually run these test files we've been inlcuding in our gemspec, I'm removing them for now. Long term after ruby-bson 2.0 is released the bson gem should include a runnable test suite in the release verison.

This change does two things:

- Removes non-functional test files from bson.gemspec
- Removes bson test suite from mongo.gemspec
RUBY-576 documentation fix for ensure index

- Syntax correction for Collection#ensure_index examples.
- Added Ruby 1.8 and Ruby 1.9 examples for Collection#create_index.
RUBY-576 Adding index type validation for hash syntax

The nested array syntax will need to remain as long as we support Ruby 1.8 but I'd like to see us start spotlighting features and syntax from 1.9+ more. I'd like to see us push people towards the new hotness in our docs and examples rather than continuing to propagate the old.

While I was correcting an issue in our docs, Emily pointed out that we don't validate index types for the hash style syntax available in Ruby 1.9. This commit fixes that and improves a few things from the perspective of code readability/maintainence.
RUBY-573 ShardingPoolManager seeds format fix