Updated rvm-capistrano gem

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>
Fixed description and summary in the gemspec

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>
Fixed assets deployment

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>
Refactored some files

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>
Bumped version to 0.6.4

Signed-off-by: Lucas Dutra Nunes <ldnunes@ossystems.com.br>