Fix #89 to allow building the app for focal

• port to Lomiri
• update Click packaging
• update Debian packaging for focal
• rename package and application by removing ubuntu- prefix
• update and move Jenkinsfile to debian/
• update .pot file

This fixes #89 (closed).

Current review errors:

- desktop:X-Ubuntu-Touch:music
missing key 'X-Ubuntu-Touch'
- desktop:required_keys:music
missing required keys: X-Ubuntu-Touch

See clickable/click-reviewers-tools#4 (closed)

- security:policy_groups_safe:music:music_files_read
(NEEDS REVIEW) reserved policy group 'music_files_read': vetted applications only
- security:redflag_fields:apparmor.json
found redflagged fields (needs human review): read_path, write_path

These have not changed.