CF-165/CF-293: add uber jar for Alex

Alex requested that we create an uber jar similar to repose-valve. 

To produce this uber jar, execute this gradle command:
```
gradle clean build uberjar
```
Then you can start the app this way:
```
java -jar build/libs/preferences-service-${version}.jar
```

A few minor changes:
* add prefix for release tag
* disable failOnUpdateNeeded, because this cause gradle to run "git status -sb" command, which failed on older version of git installed on Jenkins node