Replace leap client texts with Bitmask.
Update README and packaging names.
pep8 fixes
Update docs/, leap-client to bitmask.
Update images, jumping guy -> rainbow mask.
Add changes file, feature 3313.
Merge remote-tracking branch 'ivan/feature/3313_rebrand-leap-client-to-bitmask' into develop
Set default port for SMTP to be 2013
Support bundled gpg