Service Status Fix

[akutz]

This patch fixes issue #293 where a stale PID file would incorrectly indicate that REX-Ray was running if the status command was issued.

[akutz]

Hi @clintonskitson,

I just verified this on a Linux system. Merging.

[0]akutz@poppy:Linux-x86_64$ sudo ./rexray service status
DEBU[0000] updated log level                             logLevel=debug
REX-Ray is stopped
[0]akutz@poppy:Linux-x86_64$ sudo ./rexray service stop
DEBU[0000] updated log level                             logLevel=debug
REX-Ray is already stopped
DEBU[0000] exiting with error code 1                    
[1]akutz@poppy:Linux-x86_64$ sudo ./rexray service start
DEBU[0000] updated log level                             logLevel=debug
INFO[0000] [linux]                                      
INFO[0000] [docker]                                     
INFO[0000] [isilon]                                     
DEBU[0000] core get drivers                              osDrivers=[linux] storageDrivers=[isilon] volumeDrivers=[docker]
INFO[0000] docker volume driver initialized              availabilityZone= iops= moduleName= provider=docker size= volumeRootPath=/data volumeType=
INFO[0000] storage driver initialized                    dataSubnet=172.17.177.0/24 endpoint=https://172.17.177.230:8080 group= insecure=true moduleName= password=****** provider=Isilon userName=root volumePath=/rexray
INFO[0000] os driver initialized                         moduleName= provider=linux
DEBU[0000] invoking service start                        os.Args=[./rexray service start]
Starting REX-Ray...DEBU[0000] trying to start service                       client=/tmp/pBYNLzigKwgREXsBsxyllGnfiUoQhiBv.sock
time="2016-02-19T18:06:01-06:00" level=debug msg="updated log level" logLevel=debug 
time="2016-02-19T18:06:01-06:00" level=debug msg="invoking service start" os.Args=[/media/psf/go/src/github.com/emccode/rexray/.build/bin/Linux-x86_64/rexray start --client=/tmp/pBYNLzigKwgREXsBsxyllGnfiUoQhiBv.sock --logLevel=debug --host=tcp://:7979] 
DEBU[0000] accepted connection                          
DEBU[0000] received data                                
SUCCESS!

  The REX-Ray daemon is now running at PID 2409. To
  shutdown the daemon execute the following command:

    sudo /media/psf/go/src/github.com/emccode/rexray/.build/bin/Linux-x86_64/rexray stop

[0]akutz@poppy:Linux-x86_64$ sudo ./rexray service status
DEBU[0000] updated log level                             logLevel=debug
REX-Ray is running at PID 2409
[0]akutz@poppy:Linux-x86_64$ sudo kill -9 2409
[0]akutz@poppy:Linux-x86_64$ sudo ./rexray service status^C
[130]akutz@poppy:Linux-x86_64$ cat /var/run/rexray/rexray.pid 
2409[0]akutz@poppy:Linux-x86_sudo ./rexray service status
DEBU[0000] updated log level                             logLevel=debug
REX-Ray is stopped
[0]akutz@poppy:Linux-x86_64$ ls /var/run/rexray/
total 0
drwxr-xr-x.  2 root  40 Feb 19 18:06 ./
drwxr-xr-x. 27 root 800 Feb 19 18:05 ../
[0]akutz@poppy:Linux-x86_64$