Implementation for issue #1319 - propagate fill_in options to Element#set
basic test for fill_in options propagation
fix warning about metadata filtering under RSpec 3
Merge pull request #1338 from jnicklas/fill_in_options

first run at issue #1319 - propagate fill_in options to Element#set
Merge pull request #1343 from jnicklas/example_group

fix warning about metadata filtering under RSpec 3