update perltidyrc and CONTRIBUTING
rename and simply test model

This will make it easier to use the test model directly in
the Meerkat::Tutorial.
partial tutorial draft
put Data::Faker into fixtures role
implement update_set
simplify creating test objects
implement update_inc and genericize operator sub generation
implement update_push
implement update_add
refactor update operator method generation
update tutorial for actual update API
implement update_pop & update_shift
implemented update_remove
reorganize Document methods and start documenting them
update deps in cpanfile
test setting deep hash field
implement update_clear
defactor update_* subs

The logic of supporting so many different varieties made it harder
to understand than just seeing a bunch of repetitive 3-line subs,
so they've been split out.
implemented reinsertion and modified _removed attribute
only allow update operators to update document