$LOAD_PATH, gemspec and dependency fixes.

Removes $LOAD_PATH munging, adds Rake as development dependency so as
not to relay on a globally-installed version, breaks out VERSION to a
separate file to avoid a dependency hell catch-22 when installing for
the first time.
Adds rspec base setup.
Converts the existing test suite over to RSpec.
Removes Test::Unit tests.
Merge pull request #15 from damncabbage/rspec

Swaps existing test suite over to RSpec
Refactored request methods to allow optional params and headers for every method.

Using hash in favour of ordered arguments.
Added helper for fetching recently modified orders.
Added create_product method.
Added update_product method.
Merge pull request #20 from zubin/refactor_request_methods

Refactored request methods to allow optional params and headers for each http method
Merge pull request #22 from zubin/get_orders_modified_since

Helper for fetching recently modified orders
Add get_brands method
Default request headers to empty hash
add get_customer_count method
accept filters on get_customers method
Merge pull request #25 from pospischil/master

Default headers to an empty hash, Add get_brands, get_customer_count methods, Accept filters on get_customers
Corrected branding, fixed broken tests, added test metrics, updated gemspec

* Changed BigCommerce references to Bigcommerce (branding)
* Added CI Reporter gem for continuous integration
* Removed rubygems references, as Bundler is being used
* Fixed broken tests by adding require for Date stdlib class
* Added legacy include lib file for people using BigCommerce namespace
* Added version component constants
* Added gitignore for Bundler gem packaging and install cruft
* Added gitignore for CI Reporter output
* Added autotest config file
Removed beta related text
Changed version components to local variables
Merge pull request #26 from sgerrand/branding_changes_and_make_gem_releasable

Corrected branding, fixed broken tests, added test metrics, updated gemspec
Update README.md

The library call is BigCommerce camelcase