Merge pull request #43 from lunks/remove-gemfile-lock

Adding Gemfile.lock to .gitignore. According to [Yehuda's post](http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/):

.gitignore

@@ -3,3 +3,4 @@ pkg/*
 .bundle
 tmp
 .rvmrc
+Gemfile.lock

Gemfile.lock

-PATH
-  remote: .
-  specs:
-    paranoia (1.1.0)
-      activerecord (>= 3.0.0)
-
-GEM
-  remote: http://rubygems.org/
-  specs:
-    activemodel (3.2.0)
-      activesupport (= 3.2.0)
-      builder (~> 3.0.0)
-    activerecord (3.2.0)
-      activemodel (= 3.2.0)
-      activesupport (= 3.2.0)
-      arel (~> 3.0.0)
-      tzinfo (~> 0.3.29)
-    activesupport (3.2.0)
-      i18n (~> 0.6)
-      multi_json (~> 1.0)
-    arel (3.0.0)
-    builder (3.0.0)
-    i18n (0.6.0)
-    multi_json (1.0.4)
-    rake (0.8.7)
-    sqlite3 (1.3.5)
-    tzinfo (0.3.31)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  bundler (>= 1.0.0)
-  paranoia!
-  rake (= 0.8.7)
-  sqlite3