Improve perf of createAlternanteImpl

- Creates return-type specific return functions that are determined at
  creation time.
- Splits off promise handling to it's own function. Overrides that use promises
  must indicate so when creating the override with the usesPromise param.
- Updates overrides that use promises
Fix nokia.file-ui error message
Merge branch 'master' of https://github.com/andreasgal/j2me.js
WIP nokia.image-processing localmsg server
Log data sent from the client, read the requested file and decode it
Merge pull request #536 from EricRahm/alt_impl_perf

Improve perf of createAlternanteImpl
Draw the image with the requested size in a canvas and transform the canvas back to a blob
Fail if the aspect value is not what we expected
Create helper function to create "unique" files
Store the new image and send the reply to the client. Fixes #525.
Remove logging statements
WIP image-processing test
Add test jpeg image
Complete image-processing test
Fix number of passing tests
Add gfx test for image-processing
Update maxDifferent according to Travis results
Implement ImageDataFactory::createImmutableImageDataRegion native. Fixes #541.
Remove WIP comment
Set mutable field in the destination ImageData object