Fixed updating of TimeEntries.
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	CodeBase/mite.net/Data/Converter/TimeEntryConverter.cs
Fixed format of 'date-at' parameters.

'date-at' always requires exactly 'yyyy-M-d' format, while all the other
date parameters work with 'InvariantCulture'.
Merge branch 'master' of https://github.com/ccellar/mite.net
Better handling of empty project budgets.
Bumped version
Added AppVeyor badge