cpdb-libs 2.0b2

Second beta release for cpdb-libs 2.0.0

• Options groups: To allow better structuring of options in print dialogs, common options are categorized in groups, like media, print quality, color, finishing, ... This can be primarily done by the backends but the frontend library can do fallback/default assignments for options not assigned by the backend.
• Many print dialogs have a "Color" option group (usually shown on one tab), so also have one in cpdb-libs to match with the dialogs and more easily map the options into the dialogs.
• Add macros for new options and choices, also add "Color" group
• Synchronous printer fetching upon backend activation (PR #21)
  Made cpdbConnectToDbus() wait until all backends activate
• Backends will automatically signal any printer updates instead of the frontend having to manually ask them (PR #21)
• Add printer-state-changed signal (PR #21)
  • Changed function callback type definition for printer updates
  • Added callback to frontends for changes in printer state
• Translation support: Translations of option, choice, and group names are now supported, not only English human-readable strings. And translations can be provided by the backends (also polling them from the print service) and by the frontend library.
• Use autopoint instead of gettextize
• Enable reconnecting to dbus (PR #14)
• Debug logging: Now backends forward their log messages to the frontend library for easier debugging.
• Use <glib/gi18n.h> instead of redefining macros (Issue #20)
• Add functions to free objects (PR #15)
• Remove hardcoded paths and follow XDG base dir specs (PR #14)
• Added javadoc comments to function declarations (PR #21)
• Build system: Let make dist also create .tar.bz2 and .tar.xz
• Add the dependency on libdbus to README.md
  libdbus-1-dev is needed to configure pkg-config variables for backends
• COPYING: Added Priydarshi Singh