[JENKINS-34628] - Bundle "Font Awesome" and "Google Fints: Roboto" dependencies to prevent failures in the offline mode (#2318)

* [JENKINS-34628] Remove dependencies with external static resources

* [JENKINS-34628] License files were added

* [JENKINS-34628] Added references in the About page

jarsigner adds signatures by updating the file itself, so we have
to run it before GPG plugin signs the bit, which happens in the 'verify'
phase.

The 'pre-integration-test' phase happens right after the 'package'
phase and before the 'verify' phase, so this is adequate.

See: https://groups.google.com/forum/#!msg/jenkinsci-users/POk8TOcwOM8/i5wn2a0MMwAJ

Otherwise jarsigner -verify complains about the lack of timestamp