Update plugin to support the latest Tx Live settings options

[diegobz]

The JS snippet got some new options the past months that can be found at: http://docs.transifex.com/developer/live/api#setting-up-transifex-live-javascript-code

Most important ones are:

• dynamic: true|false (more info)
• staging: true|false (more info)

Also it would be useful to be able to disable the language selector altogether by setting the picker option to null. Tx Live has an API the allows you to control the language selection on your own way, when you want it.

Thanks for the nice plugin!