--use-leap-wheels sets --trusted-host (remove it when we have a proper
  cert) and WHEELHOUSE to https://ftp.lizard.leap.se

Until we get ftp.lizard cname, use lizard as the wheels server.

generate_wheels uses $WHEELHOUSE to generate and store the wheels for
requirements.pip and requirements-testing.pip (if it exists).

pip_install_requirements.sh installs requirements.pip from them if
possible (if not, then it fetches them from pypi) or, if passed the
--testing flag, it installs requirements-testing.pip.

- update pip
- install base reqs, with insecure flags for dirspec. fuck canonical.

While testing the way that its implemented now, I found out that no check
is being made on certificate attributes against the host.
I found this simple way of creating a BrowserLikePolicyForHTTPS using
a self signed cert and it worked on my test. I used test_https from
Soledad for checking this (which we are fixing on another branch).

Also, we don't want to depend on twisted for other things than
leap.common.http.

Before this commit, protobuf and protobuf.socketrpc were used to serialize and
transmit messages between events clients. This change implements a simpler ZMQ
client/server events mechanism that uses ZMQ sockets for transmitting messages
from clients to server and to redistribute such messages to subscribed
clients.

Closes: #6359