fix to grunt 0.3.17 as not 0.4 compatible.
rebuild lib.js and lib.min.js up to commit 18bbddb
hint revision needs to be four-parts
remove whitespace
add context to Upload model to allow sending data-context

- allows for not polluting the session object, or when the session
  object isn't suitable for passing additional context information
restore changes to lib.js from commit 4b8e9b3
restore custom header support from commit 25a64d2
restore commit ae9f867
restore commit 35d2437
restore commit to JS from f5e0c89
fix spelling error caused in commit restore