(#514) - Add grunt-cli to build instructions

In grunt 0.4 the cli tools are in a separate package
called grunt-cli. You need to install it instead.
(#543) - Encode empty attachment buffers
(#543) - Simplify and cleanup
(#545) - Ensure database doesnt exist before testing
(#545) - Fix database name in skip setup test
Merge pull request #539 from vmx/add-grunt-cli

(#514) - Add grunt-cli to build instructions
Merge pull request #543 from nick-thompson/543-leveldb-getattachment-encode

LevelDB adapter _getAttachment ignores opts.encode when returning an empty attachment buffer