Add dotenv_role config variable
Execute dotenv:symlink for all roles
Enable execution of interpolated shell commands

at least for ruby >= 1.9
Disable interpolated shell commands for Ruby <= 1.8.7
try to fix specs on ruby 1.8.7/ree
Merge pull request #69 from jcamenisch/shell-command-interpolation

Enable execution of interpolated shell commands
Merge pull request #62 from garno/feature/dotenv_roles

Add dotenv_role config variable
Merge pull request #73 from bkeepers/fix-build

Fix specs on ruby 1.8.7/ree