Update gemspec
Bump version to v1.2.1
Force to use SSLv3 to avoid SSL timeout error

This problem may be related to:
- http://rt.openssl.org/Ticket/Display.html?user=guest&pass=guest&id=2771
- http://d.hatena.ne.jp/jovi0608/20131106/1383724662
Specify user_agent
Specify as3=1 for nm* videos by default

- Can be disabled with options[:as3] == false