Glimmer 0.5.0 JRuby/SWT/API Upgrade

Glimmer 0.5.0 desktop development library for Ruby has been released with the following changes:
- Upgraded SWT to version 4.15
- Upgraded to JRuby 9.2.11.1
- Refurbished/refactored Glimmer code design and APIs getting a performance boost
- Scraped XML and multi-DSL support
- Renamed `#add_contents` to `#content`
- made it configurable to include SWT Packages or not
- Supported color keyword for standard colors
- Supported swt keyword for style
- Supported async_exec/sync_exec keywords in Glimmer DSL directly
- Changed "def body" to body { } in custom widget/shell
- Renamed commands to keywords in Glimmer
- Made Glimmer::Launcher automatically figure out dev mode when run as bin/glimmer locally
- Added LOAD_PATH explicitly

https://github.com/AndyObtiva/glimmer/tree/v0.5.0

Example of newly improved Custom Widget support: