test all WriteMakefile arguments
MIN_PERL_VERSION is harmless; leave it

This bit of code was added in commit 5c6a1202 but there doesn't seem to be any
need for it there.  We can still add a 'use' line, while keeping this data --
which also is added to MYMETA.*.
also get the minimum perl requirement from configure and test prereqs
also fold configure-requires prereqs into %FallbackPrereqs
Command 'add': load Path::Class and File::pushd only on 'execute'

... because every Command plugin is loaded even if not called, so
plugins must use lazy loading.
Amend [MetaTests] documentation to remove mention of Test::CPAN::Meta being optional

This test was changed in 878689147 to require Test::CPAN::Meta instead of
skipping the test when not installed.

This closes #295.
skip building manpages when using [MakeMaker] (for builds, not installs)

Conflicts:
	Changes
	lib/Dist/Zilla/Plugin/MakeMaker/Runner.pm