Updates Plupload to version 1.5.4.

The JavaScript, Silverlight, and SWF files had 
changes. The stylesheets did not have any changes.

Plupload release notes:
  1.5.4: http://j.mp/Plupload154
  1.5.3: http://j.mp/Plupload153
Fix: Error "Illegal nesting: nesting within plain text is illegal." in haml example
Updates Plupload to version 1.5.7

http://www.plupload.com/punbb/viewtopic.php?id=3711
sets rails >= 3.1
Merge pull request #21 from matiaskorhonen/1.5.7

Updates Plupload to 1.5.7
Merge pull request #22 from lucasrenan/rails4

rails 4 compatibility
Merge pull request #12 from whitehat101/master

Fix: Invalid haml in example
Updates for Rails 4
Don't mention Rails 3.x
Adds licenses
Merge remote-tracking branch 'upstream/master'