Use https://rubygems.org as source in Gemfile

Per latest recommendations for downloading gems:
http://bundler.io/v1.3/gemfile.html
Remove Gemfile.lock from git

Per recommendation:
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
Update implementation of jaccard_index

Uses set operators to find intersection and union of given
enumerables
Merge pull request #9 from rossta/ignore_gemfile_lock

Remove Gemfile.lock from git
Merge branch 'https_rubygems' of @rossta
update documentation
WIP levenshtein recursive implementation
levenshtein implementation with dynamic programming
handle deletion by reversing order of loops
levenshtein spec contexts for arrays and strings

levenshtein spec contexts for arrays and strings

remove extra gems
adds levenshtein wikipedia entry to README
documentation for levenshtein algorithm
Merge pull request #12 from rossta/levenshtein

Adds Levenshtein distance measure
Merge pull request #11 from rossta/bug_fix_jaccard_index

Update implementation of jaccard_index
namespace chebyshev
namespace cosine and euclidean
namespace remaining modules

including maxmin, minkowski, tanimoto; updates callbacks
for cosine, tanimoto
use instance_eval and class_eval to add functionality within modules
add regression specs for ensuring both include and extend work as expected
add specs for including levenshtein module