0.7.0

• add option and environment variable alternatives for all settings
• add setting to specify timezone for display
  • setting : TIME_ZONE
  • option: --time-zone <value>
  • environment variable: WORKEDON_TIME_ZONE
• fix usage of date/time formatting settings
• BREAKING (for advanced users only): removed the db and conf
  subcommands and moved their options under the main workedon
  command to free up reserved keywords db and conf.
  • workedon db --print-path is now workedon --print-db-path
  • workedon db --vacuum is now workedon --vacuum-db
  • workedon db --truncate is now workedon --truncate-db
  • workedon db --version is now workedon --db-version
  • workedon conf --print-path is now workedon --print-settings-path
  • workedon conf --print is now workedon --print-settings
  • all above options are now hidden from the help text