Adding basic ignore entry for example and main build directories.

Altered the rake build so that it passes. The example_3 shows off
some failing tests, so the rake build has to ignore those.
Update .gitignore file with executables from examples

This resolves #219. When generating a new module, if all the files to
generate already exist then it fails as before. If some of the files
already exist, then the files that need to be created are created. Any
existing files are not changed.

Also added a bunch of tests for this feature via rspec. Run them from
the test folder with `rake spec`.

Added directory task to create temp build/ folder, and added .gitignore to prevent this new folder form being tracked by git.

Added directory task to create temp build/ folder, and added .gitignore to prevent this new folder form being tracked by git.