Added basic composite type.

It currently does not support any of the slice features.
Added support for returning composite columns.

Added round trip test.
Added ability to make composite slice queries.

Composites have the concept of inclusive and exclusive composite
queries. For example a column range query using composites:
  :start => Cassandra::Composite.new("foo")
  :finish => Cassandra::Composite.new("foo", :slice => :inclusive)
will return all columns whose first component is "foo".
Likewise you can say:
  :start => Cassandra::Composite.new("foo", :slice => :exclusive)
which will give you all columns greater than "foo", but not foo
itself.
Changed composite slice args to [:before, :after].

Inclusive and exclusive didn't really work b/c the values
are different if it is the start of the slice vs the end
of a slice. Before/after better represent what this actually does,
appending either a negative or positive value between composite
components.

Fixed comparison logic so that the mock class works.
Merge branch 'master' into composite_columns
Fixed fetching a single composite column
Batch updates for counters

Runs through the mutate API instead of the dedicated counter API
Merge pull request #115 from nearbuy/composite_columns

Initial support for composite column names
fix the get and get_range with counter super column
remove debug code
test case for https://github.com/twitter/cassandra/issues/144
Add composite column and 1.0 files to the gemspec

Also updated the homepage and added a git ignore for the build gem file

Fixes #147
Merge pull request #145 from behrangj/master

fix for https://github.com/twitter/cassandra/issues/144
Merge pull request #141 from nearbuy/batch-add

Batch updates for counters
Fix link to issue tracker
Bumped verion to 0.13.0

This doesn't have huge new features but it does require upgrading
the thrift libs.
Faster Cassandra::Composite#hash

Old one was silly

On my box this speeds a multiget from ~9k col/s to ~12k cols/s
Don't parse composite columns twice in #initialize

This improves fetch performance by around 15%
Even faster Composite#hash

Up from 15000 columns/s to 17000 columns/s
Use the accelerated thrift binary protocol, if available

This speeds up Nearbuy's workload by almost 25%