Add WrapResult for returning HTTP::Response

Optional constructor argument `wrap_result` will return a
Net::Twitter::Lite::WrapResult object which includes both the Twitter
API result and the HTTP::Response. WrapResult provides methods for
access each as well as methods for accessing rate limiting information.
Tests for the wrap_result functionality.
Merge pull request #15 from TheWatcher/wrap-result

Tests for the wrap_result functionality.
Add accessors manually to avoid a new dependency
Prepare for release
Contributor update for wrap-result tests.
Merge pull request #16 from TheWatcher/wrap-result

Contributor update for wrap-result tests.
Fix typo