Openfile (FakeFS) fix to honor previous writes - set content in fake file upon constructor - using NewFakeFile Constructor for openfile
Openfile (FakeFS) fix to honor previous writes
- set content in fake file upon constructor
- using NewFakeFile Constructor for openfile

[#102091246](https://www.pivotaltracker.com/story/show/102091246)

Signed-off-by: Luke Woydziak <5ec47d3d6d41d8ebc18a534604a07e736a0a4783@emc.com>

cloudfoundry/bosh-utils,cloudfoundry/bosh-utils