SSH Job should export environment variables containing blanks properly

Current Situation
If an environment variable on the host running the JobScheduler contains blanks in the key, the blank is not masked. Therefore further issues can occur, e.g. an environment variable like powmig path will be exported to SCHEDULER_MASTER_POWMIG PATH where the blank results in overriding the path variable on the remote host.

Desired Behavior
Blanks in the key of an environment variable should be masked as _ to prevent subsequent errors to occur.