Fix `.htmlhint` lookup

Changed empty string default path to @cwd. While the empty path fixed the crash, the .htmlhintrc file was not being loaded properly if it

v0.0.12

Notable changes

• Provide sanity check when getting htmlHintRcPath. Fixes #9
  Related to steelbrain/linter#477 and steelbrain/linter#480 this adds a safety check to prevent an error from being thrown when the path is not set.

v0.0.9

New Features

• Allow customizable path and filename for .htmlhintrc