cpanfile ignored during build process

[tmiklas]

Issue:
The empty cpanfile located in the template is always used during the build, ignoring any other cpanfile that user may create. This results in container with missing dependencies - not working at all unless there is no dependencies beyond core Perl module set.

Suggested fix/workaround:
Move cpanfile into function directory within template, copy directory first and use cpanminus rather than Carton to install dependencies from it.

Note:
Switching to cpanminus should also remove the need to use carton exec in fprocess and effectively remove one level of wrapper as library paths are added to main.pl anyway.