Add travis-ci config

Bump version number to 2.4.2.1

Bump version number to 2.4.2.0

getPeerId was added.

Bump version number to 2.4.1.2

This commit was recreated from the 2.4.1.2 release, which commits were
somehow lost (i.e. not pushed to GitHub).

Bump version number to 2.4.1.1

Bump version number to 2.4.1.0

Bump version number to 2.3.2.0

Bump version number to 2.3.1.1

Bump version number to 2.4.0.1

Add missing import