Ignore /go directory

The /go directory is created by following the build instructions.
It is managed using mercurial. Git should ignore it.
Merge pull request #7 from jackpal/patch-1

Ignore /go directory. Thanks @jackpal.
Add LICENSE (BSD 2-clause)
added /ndk-toolchain to .gitignore
Moved example to new hello-gl2 subdirectory
renamed hello-gl2
renamed hellogl2 package
rename go package
rename library
removed redundant consts
Added nativeactivity example
updated README.md to describe the nativeactivity example
README.md update
README.md update
Added reference to https://code.google.com/p/apk-resigner/ where the signapk.sh script is from