Fixed bug in the YouTrack filter. The issues should be searched for by 'resolved date', not last date of updating.

references #28
Added a new method to get the 'TaggedCommit' for the first commit.

references #28
Changing the FromTag argument to be the AllTags argument.

references #28
Making sure that each release always has an end date. Currently using the start date from the starting tag.

references #28
Searching for closed issues from the end date of the oldest release.

references #28
Fixing unit test failure.

references #28
Merge branch 'master' into issue/fromtagfirsttag
Merge pull request #35 from pvandervelde/issue/fromtagfirsttag

When specifying 'FromTag all' the issues closed for the first tag aren't included