No Versioning for Generated Forms

Removes awesometts/forms/*.py and introduces a .gitignore instead.

Python files in the forms/ subdirectory are generated programmatically
by the tools/build_ui.sh script, and do not need to be entered into
version control.
Executable UI Builder

Marks the tools/build_ui.sh script as executable so that it can be run
directly from the terminal without explicitly sourcing it.