put origin adapters and target adapters separately
add spec for Deployable class
add example deployables.json for tests
add Deployable class
add a find singleton method to deployables array
put specs for each type of adapter separately and more

Also, this commit has some changes to heroku_spec.coffee. These changes are about the initialization of the tested
HerokuAdapter object. It has changed to use environments.
change to use environments and to expect an env as parameter for certain methods
change to init use target adapter correctly
change to use messages property
change to fullfil origin adapter definition
change to be simple while constructing other application parts
change to use new syntax of Deployer.deploy method
expect some singleton methods on deployables array