First pass at changelog for 0.12.4
Bump performance to 0.12.4, finalize changelog
Bumped version to 0.12.14
Bumped version to 0.12.4
cleanup rake routines
deduplicate subgem lists
remove deprecated cache functionality

Conflicts:
	padrino-cache/lib/padrino-cache/legacy_store.rb
use Hash#eack_key
cleanup and improve helpers
refactor test system
allow Padrino::Rendering on stdlib ERB
add travis run for stdlib-erb
use stdlib ERB lazily if no erb gem was bundled
emulate basic Sinatra set for Padrino::Mailer