Update FileJobManagement to store param passed in from System properties and environment variables



  - This enables command line testing of DSL jobs that use build parameters.

Below is a bash script that create a job dsl file named simple.job  It is parameterized to use String build parameter named JOB_NAME_PARAM.  The final line of the script sets an environment variable on the command line and invokes gradle wrapper to run the job from the command line

__SCRIPT_BELOW__
 #!/bin/bash
OUTFILE=simple.job
(
cat <<'EOF'
def jobName="${JOB_NAME_PARAM}"
job {
    name "${jobName}"
    scm {
        git('git://github.com/jgritman/aws-sdk-test.git')
    }
    triggers {
        scm('*/15 * * * *')
    }
    steps {
        maven('-e clean test')
    }
}

EOF
) > $OUTFILE

JOB_NAME_PARAM="DSL-Tutorial-1-Test-param" ./gradlew :job-dsl-core:run  -Pargs=$PWD/simple.job