Fixed issues uploading config.g and temp buttons

Fixes bug whereby when a file was uploaded to the/sys directory, the
stored file would be named after previous upload filename. Also enabled
temperature buttons during SD card printing.
Improved upload speed a little
Use new features in firmware 0.59e-dc42

Added caption to layer time graph. Display machine name instead of
"RepRapPro Ormerod". Display filament used, layer height and
generated-by data when printing from SD card if available. Increase
upload buffer to 2000 bytes for faster uploads.
Version 0.90: changes for firmware 0.65e-dc42

Changed to number extruders from 1 instead of from 0.
Merge pull request #11 from dc42/master

Various changes, see detailed description