Top-level '/tpl' and '/tple' aliases can now be changed + helper tweaks

The top-level Template alias paths are no longer hard-coded, and can be
changed via 'Controller::RapidApp::Template' config params. The defaults
are still the same which are:

  read_alias_path => '/tpl',
  edit_alias_path => '/tple'

They can also be optionally disabled by setting value(s) of undef or 0
(false)

Also updated the base config generated by RapidApp::Helper to provide
more verbose comments. Also, the new 'RapidApp' config key is now
generated instead of 'Model::RapidApp' (see previous commit)