Add replacement for file_upload.py service

[fnoop]

Related to goodrobots/maverick-api#230 and goodrobots/maverick#955, there needs to be a replacement facility to upload dataflash logs to mavlogd for processing.
file_upload.py could be moved to maverick project and served out through nginx for the immediate future, until a better alternative can be built into -api.
In the meantime, a simple upload interface to this facility needs to be added to -web to allow users to simply upload files.