drop use of MooseX::MarkAsMethods

[karenetheridge]

with Moose 2.1400 and namespace::autoclean 0.16, MXMAM should no longer be needed.

[vanstyn]

Fixing this in RapidApp either requires fixing it in DBIx::Class::Schema::Loader - RT#100004 (https://rt.cpan.org/Public/Bug/Display.html?id=100004) or regenerating the CoreSchema classes without use_moose. I don't want to edit directly because this will prevent regenerating later...