[BACKLOG-186] - Need to provide user with a decent message when the repository is not availabe

changed error message according to UX feedback
slightly changed logic for process launch of Repository Explorer failure
added failure processing for JobDialog: extraTabs

[BACKLOG-186] - Need to provide user with a decent message when the repository is not availabe

change ctor of KettleRepositoryLostException to rely on super getMessage() and getLocalizedMessage()
checkstyle

[BACKLOG-186] - Need to provide user with a decent message when the repository is not availabe

fix typo in the message

[BACKLOG-186] - Need to provide user with a decent message when the repository is not availabe

move the second message to the same package with repositoryLostException
in order to avoid strings as package names while loading string resources
Merge pull request #773 from mtseu/backlog-186-52

[BACKLOG-186] - Need to provide user with a decent message when the repository is not available
[PDI-12974] Move Modeling category below Big Data and above XML categories in Spoon