Null values should be removed

[MoonBow-1]

Closely tied to #15

Methods should throw Exceptions instead of returning null values.

[MoonBow-1]

Removing null values and switching to exceptions caused some captures to not be sent, investigating the reasons currently. At least one of the reasons was a RELP capture missing the "relp" from the directory name.

[MoonBow-1]

Actually seems that it's more about HostGroups. About 50 of them are not sent compared to commit ddd035c2

[MoonBow-1]

Pinpointed this issue to commit 6365df6b, will check the changes and fix this.

[MoonBow-1]

Fixed most of the missing things in commit 19cedc49, but 1 capture and 1 host are still not sent, going to investigate this

[MoonBow-1]

Going to put this small problem on the back-burner for now, going to fix the rest of the null returns first

[MoonBow-1]

HTTP client has been refactored to throw Exceptions instead of returning null

[MoonBow-1]

All null return statements have been removed in commit a3fd3a25