Fix a non fatal exception during a testrun when injecting LDAPSecurityRealm.

org.apache.commons.io.input.AutoCloseInputStream was introduced in commons-io version 1.4. The stapler dependency made maven select the 1.3.1 version of commons-io.
Set the default to true, instead of setting the checkbox to true everytime. Change field to public to get the current value properly displayed in the advanced section.
Merge pull request #47 from spark404/fix-compileerror

Fix a non fatal exception during a testrun when injecting LDAPSecurityRealm
Merge pull request #46 from spark404/fix-default

Set the default to true, instead of setting the checkbox to true every time.
Fix excess workload logic to not spawn as many instances