Chirp Allocations using CFS

This pull request cleans up chirp_alloc:

o It now uses the CFS layer for access to the file system.
o A lock method was added to the CFS layer. Only local implements it.
o chirp_server now has the implementations of getstream/putstream/rmall since they do not really belong in another module (chirp_alloc).
o chirp_alloc now has a simpler interface like chirp_acl, most requests are funneled through chirp_alloc_realloc.
o 2 new test cases which weakly cover thirdput and alloc.

Fixes #244.