Rewrite dancer2 cli #371

Hi,

I've made some efforts to rewrite dancer2 cli. Issue 371. The new tool (dancer2-cli) uses App::Cmd which makes it flexible and easily extensible. I also split all skel files out of dancer2 into share/skel directory and used File::ShareDir for getting access to them.

My initial idea was to replace original dancer2 script. However, an attempt to keep 100% backward compatibility forced me to make several ugly hacks in different places of the code. Since the hacks are global to dancer2-cli it could negatively influence behavior of future commands. I decided that it's a good idea to concentrate all backward-compatibility staff in one place, such as wrapper around dancer2-cli. So, now dancer2 just slightly modifies ARGV and runs dancer2-cli. We can consider dancer2 tool to be deprecated and delete it later.

Please let me know if there is any issue with my code.

Thank you.