[FEATURE] Add an option to rewrite links

Twitter introduces an own link shortner. This is used in all tweets
returned from the api. This patch adds a new plugin option to rewrite
all links to the entered one.

Releases: 1.1
Change-Id: I1d059772afa37914f07e3f4cfe648fdc3b1b2ca6
Reviewed-on: https://review.typo3.org/25378
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes