Improved logging in JiraIssueTracker and YouTrackIssueTracker. ILog interface is now passed as a Constructor injection, just like that is already done in GithubIssueTracker.
Fixed an issue with JiraIssueTrackerTest.
Added common instance of Log to all the issue trackers.
Merge pull request #56 from MitjaBezensek/ImproveLogging

Improved logging in JiraIssueTracker and YouTrackIssueTracker.