Do not specify version constraints explicitly

* http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
No need to require "rspec"
Pry is already in the gemspec
Explicitly require v1.9.3 or above
Added extra Ruby versions to test plan
Merge pull request #2 from sgerrand/require-ruby-version-1.9.3

Require Ruby version 1.9.3
Autoconfigure with no experiments initially
Add posibility to choose other functions
Supports version 0.0.1 experiments + you can choose other algorithms with the new nomenclature
Update README
Update gem version to 1.0.0
Extract shared examples for reuse
Implement MD5 weighted split function
Set Ruby version
Merge pull request #5 from FraDim/development

Add 'MD5 weighted split' function
Establish the deterministic nature of the algorithm

devs: @jpstevens & @fradim
Update README

devs: @jpstevens & @fradim
Merge pull request #6 from FraDim/md5_tests

Establish the deterministic nature of the algorithm
Change version to 0.1.0
Allow subclasses to reuse WeightedSplit methods
Add HeavisideWeightedSplit to functions