plugin: provide stdin in command execution
tsuru: bump to 0.11.1
plugin: overwriting the environ with the tsuru envs.

thanks @fsouza.

Conflicts:
	tsuru/plugin.go
	tsuru/plugin_test.go
main: bump to 0.11.2
Merge tag '0.11.2'

Conflicts:
	tsuru/main.go
	tsuru/plugin_test.go