Removes useless spaces

When running "rvm install 2.0.0" the output says:
ruby-2.0.0-p247 - #configuring......
ruby-2.0.0-p247 - #compiling......
ruby-2.0.0-p247 - #installing ......

This commit removes the space at the end of "# installing" to make it
more consistent with the other outputs ("configuring" and "compiling").