Release 0.3.1

[rafamizes]

@rultor release it; the tag is 0.3.1.

[rultor]

@rultor release it; the tag is 0.3.1.

@rafamizes OK, I will release it now. Please check the progress here

[rultor]

@rultor release it; the tag is 0.3.1.

@rafamizes Done! FYI, the full log is here (took me 2min)