updated argument handler to work without callback

The method seems convoluted, but correctly applies the callback.  Please feel free to update it if it is too long.
Throw a ReferenceError on unknown list in `keystone.list`
Adds appversion rendering to footer
Merge pull request #760 from sebmck/unknown-list

Throw a ReferenceError on unknown list
Merge pull request #757 from snowkeeper/email

Email - updated argument handler to work without callback
Cleaning up linter warnings in lib/email
Cleaning up linter warnings in core/initNav
Fixing redefinition of Promise and other linter warnings in core/mount
Extraneous semicolon in core/populateRelated
Fixing templateCache bug in core/render
Fixing linter warnings in fieldTypes/localfiles
Fixing linter warnings in fieldTypes/numberarray
fieldTypes/textarray
Calling the localFile formatter with the field scope
Switching to from mv to fs-extra.move
Fixing href and formatter functionality in localFile type
Overwrite existing files by default in localfile
Cleaning up localfile.prototype.href
Bringing localfiles into line with localfile, fixes #700
Updating changelog