Allow ignoring raids without a reward

[Lokorin]

Status: Included in version 1.4.0

Problem
Currently all intervals have to be uploaded, even if they do not contain any reward. This is good for getting a better view of the participation, but can sometimes be unnecessary.

Suggestion
Add an option in the Server configuration tab named something like "Ignore intervals without rewards" in the form of a checkbox. Checking the checkbox should make it so that intervals with a total reward equal to 0 are ignored upon uploading the day to the server.

Things to consider
An analogous "Ignore events without rewards" option should probably also be included for completeness sake.

How the code should be modified
Simply modify the uploadIntervalsAsIndividualRaids, uploadIntervalsAsRaidBatch and uploadEvents methods in the Server class so that they filter the intervals and events prior to beginning the upload. The two methods for uploading raids should be refactored to avoid duplicated code.

[Lokorin]

An "Ignore loot items without price" option should probably also be added.