Chore/update to rails 4.1 and ruby 2.1.1/70507552

Cleans up dependencies:

- adds unlisted `timeliness` runtime dependency
- adds `rubocop` as dev dependency
- uses released-to-rubygems version of `netsuite` gem (see 940f225)

(Can't use rubygems version of `netsuite-rest-client` because they deprecated the gem.)
Rubocop gives me this....

Offenses:

spec/support/have_failed_matcher.rb:9:61: C: Space inside empty braces detected.
    given.is_a?(::Given::Failure) ? -> { given.call } : -> { }
                                                            ^

26 files inspected, 1 offense detected