sort flowconfig option parsers
sort flowconfig option parsers

Summary:
hoisted all of the nontrivial flowconfig option parsers into helper functions, so that all of the items in the `parsers` array are one-liners and can be kept sorted.

this just makes it easier to read and to add new ones without merge conflicts.

Reviewed By: panagosg7

Differential Revision: D25888604

fbshipit-source-id: 4b139a3222153046567c9bd17b549a2b219a2958

facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow