patch to handle debugfs not mounted

[vaishnavachath]

I have tried to add a patch using shelljs to handle the case when debugfs is not mounted(Issue #61 [still exists]).The issue is solved after adding the patch and I also did note the run-time before and after the change(for this example script: http://beagleboard.org/Support/BoneScript/getPinMode/), the results are :

before making the change :

real 0m8.573s user 0m7.748s sys 0m0.564s

after making the change(when debugfs already mounted) :

real 0m8.783s user 0m8.068s sys 0m0.516s

after making the change(when debugfs not mounted) :

real 0m10.074s user 0m9.192s sys 0m0.680s

[coveralls]

Coverage remained the same at 35.912% when pulling e03ad17c6f485b5de3db2ad400600896c45c1090 on vaishnav98:master into 2148f35a4217f036eaf5faed43310a7fc2397fcb on jadonk:master.

[vaishnavachath]

I just found that using shelljs was actually a slower alternative than doing .exec() , did not know about it earlier will fix it while submitting another patch.

[vaishnavachath]

https://github.com/beagleboard/bonescript/issues/16