remove recipes feature

more details:

creating a gem just for a single line of deploy
script is overkill and not agile. Therefore, now
removing all traces of the recipe feature.

This makes allows me to remove a lot of code and
finally implement the multistage deploy feature,
as we can just add hooks for different rake tasks
throughout deployment.
run on multiple rubies
remove obsolete spec
remove repository dsl method
clean up RVM/rbenv stuff

Considering the fact that rbenv requires less 
setup I am considering it as a default. Since most
recent RVM versions support loading via
.ruby-version file, this should also work out of
the box with most rvm setups. Just specify the
scripts to load with env_scripts and if they don't
already source your rvmrc then just set
source_rvmrc in the blazing config.
refactor new rbenv/rvm setup

- rename env_scripts to env_script as we actually
load one script
- remove anything rvm/rbenv specific. People can
load their own env by specifiying env_script,
should work for everyone.
simplyfiy passing env variables around

- rake DSL method no longer accepts env as second
argument

- RAILS_ENV and any other env variable can be set
per target as a target option