update version name and .npmignore

increase to 2.6.0 as we'll start package with the apk
at least for testing purpose.
remove experimental dir from the npm package.

Release 2.5.0

2.4.0

2.3.0

2.2.0

2.1.0

2.0.0

1.4.0

1.3.0

1.2.0