Feature/ukigumo server

ref #9

It become a big branch. Please review it.

- add script/ukigumo-server
- introduce Amon2::Plugin::ShareDir and move resource files to share/
- add Ukigumo::Server::Launcher for common processing of script/ukigumo-server and app.psgi
- fix testing. app.psgi is not needed in testing any more
- change config file loading policy

Ukigumo::Server is depend on perl5.10 or higher ordinally, then I used features of perl5.10
somewhere.