Fix the way spinsv kills the process

Now spinsv sends SIGTERM followed by a configurable grace period
before a SIGKILL. User defined kill commnad precedes above if
given.

Previous behavior would run the custom kill command without any
guarantee that the process actually gets killed.

Patch by Omid Aladini <omid@soundcloud.com>
         Emily Green  <em@soundcloud.com>
Bump spinsv's version for the fix to kill processes
Merge pull request #1 from omidaladini/fix_spinsv_kill

Fix the way spinsv kills the process