minor: make gemspec point to 2.0.0.rc0
minor: enforce expect syntax for RSpec
minor: add test db and test collection constants
minor: increase coverage requirements and restrict to java platform
minor: remove superflous versions and allowed failures
minor: add json to Gemfile for Ruby 1.8.7
minor: bump bson to rc1
RUBY-595: Message base class, Serializers, BitVector
RUBY-595: wire protocol messages
RUBY-595: specs for wire protocol
beginning specs and cursor