juju resources needs to support extensions other than ".tgz"

[Matt Bruzek]

I am trying to write docs for the resources feature and I found that ".zip" is not a valid extension.

```
juju deploy ../trusty/resources-example --series trusty --resource software=consul_0.6.4_linux_amd64.zip
ERROR PUT https://54.165.203.172:17070/model/222633d3-247a-474a-88dc-8c7a501fe3a7/services/resources-example/resources/software?pendingid=6d9225a8-b75b-44b8-8b95-f3f87262477f: incorrect extension on resource upload "consul_0.6.4_linux_amd64.zip", expected ".tgz"
```

Different software is packaged in a variety of methods. We are not asking our users to repackage their files into tgz just for Juju are we?

I thought resources handled binary blobs. Why does resources even care what extension this file is? Can we fix this?

[Charles Butler (lazypower)]

+1 support your local zip distributor

[Katherine Cox-Buday (cox-katherine-e)]

What extension is declared in the charm's metadata.yaml?

[Matt Bruzek (mbruzek)]

yeah I see that I used software.tgz in the metadata.yaml file. Sorry for the noise.