Rename 'Connection' to 'Client'

As the 'Connection' class does not really represent a connection,
rename it to 'Client'.
Rename 'Util' to 'Utilities'

The latter is more Ruby-like.
Use 'module_function' in Utilities
Include 'Utilities' where appropriate
Merge pull request #16 from jvirtanen/cleanups/utilities

Clean up 'Utilities'
Merge remote-tracking branch 'jvirtanen/cleanups/client'

Conflicts:
	lib/reittiopas2/client.rb
	lib/reittiopas2/routing.rb