Support for explicit reservation in taskfs

Here is the 4cff22b0ac revision which supports res command on ctl file. This involves few fundamental changes in how reservation is done. Remote reservation is moved from clone file read to ctl res command. The ctl exec command and stdio, status, stderr files are modified to to verify if remote resources are allocated or not before doing anything. If no remote resources are reserved, then No remote reservation done error is returned.

Currently, remote reservation of only one node is supported. Next revision of code will hopefully support multiple remote reservations and executions.

Following is the demo execution of how one can use this.

; cd /task/remote
; cat clone
0; cd 0
; echo exec pwd > ctl
echo: write error: No remote reservation done
; cat status
cat: read error: No remote reservation done
; echo res 1 > ctl
echo: write error: No remote resources available
; mount -A tcp!127.0.0.1!6666 /remote/host2
; echo res 1 > ctl
; echo exec pwd > ctl
; cat stdio
/home/pravin/projects/inferno/ericvh/ericvh-brasil
; cat status
cmd/0 3 Done /home/pravin/projects/inferno/ericvh//ericvh-brasil/ pwd
; cat stderr
;

Above output shows how ctl exec command and status behaves
before and after ctl res command.