Update .gitignore:

- sort
- add rbenv and RubyMine configuration

Author: dschweisguth

.gitignore

@@ -1,16 +1,20 @@
-/doc/
-/pkg/
-/tmp/
-.rbx/
-.#*
-.DS_Store
-*.dSYM
+*.bundle
 *.class
+*.dSYM
 *.jar
-*.bundle
 *.o
 *.rbc
+.#*
+.DS_Store
+.rbx/
+/.idea
+/.rbenv-gemsets
+/.ruby-gemset
+/.ruby-version
+/Gemfile.lock
+/doc/
+/pkg/
+/test/database.yml
+/tmp/
 Makefile*
 mkmf.log
-/test/database.yml
-/Gemfile.lock