Fix extension install

[lfuelling]

Hi,

as mentioned in #28 I'm trying to get the installation of extensions without a .pub file to work (using the public key in the manifest.json).

The modification I made will use the key property of the manifest in case there is no .pub file available.

Unfortunately there is something buggy and while the extension (.crx) and the accompanying .json file are copied into the External Extensions folder, the extension doesn't show up in chrome://extensions.

[peter-h-ncc]

Hi!

I'm now looking after this repo, I notice this pull is from quite some time ago, so before I merged it I wanted to ask about this line:

state: 1 # this will soon be deprecated, better to use disable_reasons right away

Is this something that should be updated before testing and merging?

[lfuelling]

I don't think so, disable_reasons is used two lines above