Partial refactor of transform_expectations

TODO: move responsibility to another module
Remove hoax_api.hrl
Remove obsolete comment
Introduce expectation record
Parse records during verification step
Change expectation record

Remove arity field, combine M/F/A fields into key field
Use expectation records in hoax_tab
Throw error if not given expectations
Remove debug io:format call
Switch to invocation handler pattern

This design should be much simpler to maintain and extend.  Also closes
#2.
Remove R15B02 and add R16B to travis
Remove package syntax from assertion

Should fix use in R16
Rename init_expect->insert
Simplify hoax header file
Move tests from hoax_module to hoax_invocation
Remove compile responsibility from hoax_module
Add explicit test for hoax_module gode generation
Reuse internal function
Add Gemfile
Bump version to 0.9.4