Improved Jira search, calendar quarters...

• Prevent exploring tests under the tmt directory
• Run unit tests always under the English locale
• Enable basic smoke test against github in packit
• Disable test for the redmine plugin
• Update test data for the redmine plugin
• Update test data for the sentry plugin
• Update test data for the gerrit plugin
• Use calendar year quarters by default [fix #223]
• Merge the improved Jira search [#198]
• Adjust improved Jira search using scriptrunner
• Use scriptrunner issueFunction to speed up things
• Simplify Packit config (copr_build no more needed)
• Update test data for the sentry plugin
• Implement Jira issue comparison to prevent dupes
• Do not break sorting on merge
• Add default command into the info log [fix #217]
• Enable Python 3.8 in Travis, update metadata