Merge pull request #9 from smontgomerie/master

Updated gem to include Custom Tracking Variables and Events
Merge pull request #14 from smontgomerie/master

Missed a conflict resolution in the last PR.
Merge pull request #15 from smontgomerie/master

Updated README
added support for ip address anonymization
removed unneeded blank in push function call
Merged in support for ip address anonymization.  Modified the flag to :anonymize_ip for Rails consistency