[PATCH] Fixed missing newline characters after gem and add_source generator actions

A generator that uses the "gem" or "add_source" actions, when executed, it generates the Gemfile wrong. It concatenate the lines, without adding the newline character at the end of the line.

You get something like this:

# Gemfile
gem "rake",  ">= 0.8.7"gem "mocha", ">= 0.9.8"

instead of

# Gemfile
gem "rake",  ">= 0.8.7"
gem "mocha", ">= 0.9.8"

Same happens if you use add_source.

This patch fixes this issue.