Add detection for Opera 15+
Merge pull request #72 from dougwilson/feature/opera15up

Add detection for Opera 15+
Bumps version to 1.64.
v1.64

    - Adds detection for Opera 15+ (Douglas Christopher Wilson)
os_version for firefox in Mac
Merge pull request #73 from swuecho/master

os_version for firefox in Mac
Bumps version to 1.65
v1.65

    - Adds os_version for FireFox in OS X (Hao Wu)