Added compatibility with `grunt` _0.4.2_

Also updated `jsftp` to _1.2.x_.
Fixed an issue with uploading multiple files at the same time.
Added a "Getting Started" section to the readme.

Thanks to @dyaa for the suggestion.
Fix issue on windows: Remote path contains \ instead of /
Merge pull request #42 from urish/patch-1

Fix issue on windows: Remote path contains \ instead of /
Allowed overriding auth credentials in the gruntfile
Merge pull request #49 from thewildandy/master

Allowed overriding auth credentials in the gruntfile
Small clarifications in the README.
Another README update.
Added warning if an `authKey` is provided and no `.ftppass` is found.
Added a "authPath" configuration option.

Thanks to @charliedowler for the initial PR and to @marcinant for the
convincing discussion.