add RSpec to Guardfile; remove Spring from there

So RSpec options can be easily configured. Removing Spring keeps specs
from running twice.
add utf-8 charset meta tag to layout
delete commented-out line (developer mode for omniauth)
make application CSS-free
configure guard bundler
add some gems
try to configure DatabaseCleaner for feature specs (didn't work)

I still get error messages regarding database conflicts when I try to
run the edit and delete feature specs.
add flash notifications to #create and #update
add markdown support for proposals
add navigation elements
add feature test for proposal
display different views based on whether user is the current user
merge first and last name database fields
delete useless files
add view to edit user profile