Extension: Pass '-n' to 'pgrep'

In order not to match any intermediate 'wrapper' scripts, a process
table lookup should only match the 'last' process.

See: ARAKOON-406
See: http://jira.incubaid.com/browse/ARAKOON-406
Merge pull request #78 from Incubaid/ARAKOON-406

Extension: Pass '-n' to 'pgrep'