Fix typo in docs

MSP-9895

@!attributes -> @!attribute
Fix PRERELEASE for branch

MSP-9895
Include app/models in docs

MSP-9895
Metasploit::Concern.run and shared example

MSP-9895

I forgot to call ActiveSupport.run_load_hooks in some other gems, so to
prevent that in the future, add a shared example
"Metasploit::Concern.run" which will check that
`Metasploit::Concern.run(self)` or the lower-level
`ActiveSupport.run_load_hooks(<name>, self)` is called for the
described_class.  The shared example itself is tested with cucumber
which can be run with `rake features` now.
Use HTML formatter for simplecov when not on travis-ci

MSP-9895

The coveralls formatter does nothing when run locally, so running `rake
spec` only produced a coverage report in Rubymine and not from the
terminal.
Simplecov + Coveralls for cucumber

MSP-9895
Filter Rakefiles from coverage

MSP-9895

There is not plan to test the Rakefile error handling in cucumber.
Fix I18n.enforce_available_locales deprecation warning

MSP-9895
Test spec and cucumber in different jobs

MSP-9895

Use RAKE_TASK environment variable to run `rake spec` and `rake
cucumber` as separate build jobs on travis-ci.
The rake task is called 'features', not 'cucumber'

MSP-9895
Expand README to cover support testing and engines

MSP-9895
[ci skip]
Optimize jruby cucumber environment

MSP-9895

Get JVM option tuning from 'aruba/jruby' and double timeout to 6 seconds
to fix timeout errors when running `rspec`.
Add timeout doubling for rbx cucumber too

MSP-9895

I can't reproduce the timeout locally with rbx, so I just have to try
the doubling that made JRuby work to see if it fixes rbx on travis-ci.
Minor typo in README fixed, ' -> `
Merge branch 'feature/shared-example'

MSP-9895 #land
Version update post feature/shared-example merge