Update dependencies
only use the field name in previous and next methods

Fixes #22
Account for possibility of weekend posting in by_direction tests
Add Travis Build Status to README
Merge pull request #25 from fny/readme

Add Travis Build Status to README
Segregate tests by db/orm; add rake test tasks
Merge pull request #26 from fny/orm-specific-tests

Segregate tests by db/orm; add rake test tasks
Kill the error-raising, rspec require radar/by_star#23
Kill the Gemfile.lock to allow for testing varying dependency versions
Allow for testing various activerecord/mongoid versions

Fixes #27
Teach Travis of our mischief :school:
- Support "Time-Range" type objects by allowing optional start and end time parameters such as:

   by_star_field :start_time, :end_time

(This is fully backwards compatible)
- Restructure classes/dirs to be more agnostic toward AR vs. Mongoid
- Consolidate shared methods between AR and Mongoid into a ByStar::Base object
- ActiveRecord should be dev dependency. ActiveSupport should be prod dependency
- Use ActiveSupport::Concern
Simply start / end accessor methods
Both before and after methods should reference start time for time-range type objects
Change order of options precedence
- Add strict mode for TimeRange type queries
- Non-strict mode (permissive) should use gt/lt rather than gte/lte
* Drop official support for Ruby <= 1.9.2
* Add Ruby 2.1.0, Rubinius, and JRuby to Travis
Move time_ext to kernel folder
Cleanup Gemspec, add Johnny Shields as co-author
Add Ryan Bigg to license