Extend EC2LatentBuildSlave to support spot instances.
Added MultipleFileUpload step.

Use this to upload multiple files at once. Supports all the options of
FileUpload and DirectoryUpload. Makes use of the "stat" command to
determine the kind of file that is uploaded. "Skips" if slavesrcs is an
empty list. "slavesrcs", "masterdest" and "url" are renderable.

    transfer.MultipleFileUpload(slavesrcs=['some/file', 'some/directory'],
                                masterdest='targetdir')
Refactored FileUpload test
Type (timestamp -> srctimestamp)

Yikes! Thank you, Travis!
obligatory pep8 commit
Manual, release notes for MultipleFileUpload
added the "missing commit" to the rebased branch
 Made small stylistic changes
add event with change universal handler
add event handle properties
Fix stupid bug
Fix stupid bug V2
Fix. List argument, bad way
Sync upstream
Added methods uploadDone and allUploadsDone
uploadDone and allUploadsDone may return deferreds
Added failure test cases
Added subclassing test
Pulled runTransferCommand up to _TransferBuildStep

Formerly runUploadCommand of MultipleFileUpload.
The runTransferCommand function adds a callback to extract the result
from the command instance and (optionally) ann error callback to
cancel the command's writer.
Added test cases for upload errors