[WIP] Build appliances from reliable git references

Previously, appliances were built starting at 8 pm sequentially and were hardcode to clone this manageiq repository and use the code at the time the clone occurs, which can occur anytime in the next hour or so.

This pull request fixes this by checking the current VERSION file to indicate what branch (master) or tag to build from.  This branch or tag is then checked to capture the git sha1 and both this branch/tag and git sha1 is injected into the kickstart to ensure we can build all appliances from the same point and name them appropriately.

As an example, if the VERSION file is **"master"** (currently):

The kickstart has the following:
```
git clone https://github.com/ManageIQ/manageiq.git $app_root
git checkout master
git reset --hard c2c9857064
```

If the VERSION file has a **branch or tag** (I used a pull request just for fun: refs/pull/1/head)

The kickstart would have:
```
git clone https://github.com/ManageIQ/manageiq.git $app_root
git checkout refs/pull/1/head
git reset --hard 9d9b205e81
```

And, the ova would be changed a below.

**Before**:
manageiq-nightly-vsphere-201406242000.ova

**After**:
manageiq-vsphere-nightly-201406242000-50fcc563c8.ova