* DAP-20916 - SSH Connections Remain Open After Import Job Completes
* remove session cache from jsch runner and replace by only storing the created session
* do not allow any longer to change connection parameters if the current session is connected
* create always a new session in case the cached session is not set or alreabledady closed
* only create debug messages in case debug is enabled
* do not let the cache expiry because we expect a defined life time
* add javadoc to disconnect method
* create constant out of error message
* make session key generation more unique
* add tests for it
* highered test coverage of JschRunner and CachedSession
* check connect state also for timeout setter
* set on disconnect the cached session property to null
update zone an ami’s to get the tests working
remover superfluous cache key and improve logging
add missing license header
 bump version to 0.7.dev