Minimum Permission to Restart SQL Services
You can  grant the Service Start/Stop right for the SQL Server and Agent service to the Developers or their Windows group.

You can use 


Use Group Policy
Security Templates or
Use Subinacl.exe


Above all are described in this KB article How to grant users rights to manage services 

As a side note, you can use sysinternals tool - accesschk.exe. It will help you to find out -


  what kind of accesses specific users or groups have to resources including files, directories, Registry keys, global objects and Windows services.