Sync split functions files

DevStack split common functions from 'functions' to the surprisingly named
'functions-common'.  Now 'functions-common' is what gets sync'ed with Grenade
(and anywhere else that may want it).  Everything should still source
'functions' as before and 'functions' will source 'functions-common'.

Any Grenade-only functions should be defined in 'functions'.

Change-Id: Id81c22dc19aad3a6fe11b1227de8d50a4a4f8c05