Update guard-rspec to 3.0.0
Enable some guard-rspec options explicitly

all_after_pass, all_on_start and keep_failed are disabled by default in guard-rspec 3.0.0.
https://github.com/guard/guard-rspec/commit/ddd0332a27c5078d9d67785a8f06600ac08061f5
Make dependency specification strict a bit
Fix Ruby 1.8 hash literal
Let Travis CI run rubocop