Update README.md

added example
Update README.md
Update README.md
Update README.md
Update README.md
Update README.md

removed typos, restructured text, added links, added info on versions of third party libraries
Add support HTTP proxy

Added support for build XAR with HTTP proxy
Specific settings can be set in local.build.properties, made file
ignored
Reformatted XML documents
Merge pull request #1 from dizzzz/develop

Add support HTTP proxy