add cpanfile to root to help travis along

Weird things happen when trying to bootstrap this package and additional
requirements are needed in the version being tested, but not the prior
version.

This should allow us to use cpanfile and cpanm to resolve that in addition to
the normal resolution process.
travis: copy cpanfile back into our root

This should help with bootstrapping problems on travis, at least.
rejigger our .travis.yml to be...  well, hopefully better

The general idea here was stolen from dist-zilla's travis config.  I realized
I was doing this backwards for dzil dev trees, as we should just let dzil tell
us the dependencies and run the tests for us.  No need to get cpanm to figure
it out on its own.
require a recent version of autodie

...the better to catch system() screwups :)
add ensure_current() method

Little helper method to assist when building packages once built with a prior
version of this package to a newer one by automating any changes we can (e.g.
ensure cpanfile is in the repo proper, README.pod -> README.md, etc).
add the PluginRemover role!

(...but no docs yet.)

Happily stolen from @karenetheridge's author bundle :)
nit!
make copy_from_build a private attribute

...and sync everything else up to it.  That is, ensure_current() checks to
make sure git knows about all of the files, they're added to Git::Commit's
allow_dirty, and used to populate CopyFromBuild's list of files, naturally.
default => builder; plus a note to clean up this area.  ew.
don't add cpanfile to build in dist.ini, as we're doing it in the bundle now
use Git::Check::Remote to ensure master and release/cpan are in sync before releasing

...too embarassing to contemplate, otherwise, really!
fixup some of the little pod we have...
start prepping dist.ini to hold our prereqs

...well, certain of them, at any rate.  Some are only really needed for
certain phases, or to ensure that they're installed when working on a
different dist (e.g. external test deps), so there's no need to load them in
our class just to ensure the prereqs show up in the dist.

Maybe.
add Test::CheckDeps

Seems like a sensible thing to do.
update cpanfile