Ensure parent dir exists while injecting files

Currently, if we inject a file to a not existing path,
the injecting will be failed with error 'No such file
or directory'.
Nova will firstly execute `mkdir -p` in folsom before injecting,
but this operation is lost from commit
72918415f2b6a241d6097a563aba55a849936591

This patch fix this bug by adding the `mkdir -p` operation as folsom.

Closes-bug: #1272829

Change-Id: If33a79c538e07cb25300db64ac7a9dee3d3b19c2
Merge "Ensure parent dir exists while injecting files"