Merge pull request #761 from mtseu/backlog-186-52

[BACKLOG-186] - Need to provide user with a decent message when the repo...
[BACKLOG-179] Exporting/Importing Jobs breaks Transformation specification when using "Specify by reference"
[BACKLOG-179] Fixing/Updating unit tests
[BACKLOG-179] Errors executing JobEntryTrans/JobEntryJob after export/import
Merge pull request #766 from mdamour1976/5.2

[BACKLOG-179] Errors executing JobEntryTrans/JobEntryJob after export/import
[BACKLOG-684] - Updated documentation header from 5.1 to 5.2
Merge pull request #770 from brendan-lynch/5.2

[BACKLOG-684] - Updated documentation header from 5.1 to 5.2
[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