Add backup to tokenmgr

Summary: Adds file import and export to tokenmgr

Test Plan: TBD

Reviewers: mhalverson, abahouth, esayle

Reviewed By: esayle

Subscribers: twilly, sshah, khayden, wpatterson, abahouth, esayle, egryaznov

Differential Revision: http://phabulous.newokl.com/D106