DO NOT MERGE:Manifest mock

Usage:

1) grab `fake_manifest.key` on your machine
```bash
cd /tmp
wget http://cosmos.lab.eng.pnq.redhat.com/rhel64/fake_manifest.key
```

2) install  `fake_manifest.cert` on candlepin server
```bash
ssh root@qetello02.usersys.redhat.com
cd /etc/candlepin/certs/upstream/
wget cosmos.lab.eng.pnq.redhat.com/rhel64/fake_manifest.crt
service tomcat6 restart
```

3) download a valid manifest (for example to `/tmp/manifest.zip`)

4) in python:
```python
from robottelo.common.manifests import clone
clone("/tmp/fake_manifest.key", "/tmp/manifest.zip", "/tmp/manifest2.zip")
```

5) `/tmp/manifest2.zip` should be an uploadable new manifest :)

Unfortunately, for now, candlepin complains:

> The archive does not contain the required meta.json file

I can't figure out why. If you'd figure that out, we have infinite manifest supply at our disposal :)