sdk: don't allow mounts in inject actions

[chrisguida]

Fixes: #557

Proof:

[dr-bonez]

since verify() is invoked on package install as well, we may need to only run this check if manifest.eos-version >= 0.3.2

[chrisguida]

I'd prefer to know on the pack/verify step. having to wait until the install step introduces lag into the build/deploy cycle

[chrisguida]

Or perhaps I'm misunderstanding

[dr-bonez]

It does both