Starts work on https as well as some moving about

I now start the listener in the main.c file rather than proxy given that
I didn't feel proxy was the right place if a normal (non-proxied)
request came in. webserver.{c,h} and proxy.{c,h} had some changes
relating to this.

The config changed slightly - we now create a folder in ~/.config/
called yaip. This is where certificates and so on will be stored along
with the user configuration

I created a helper function to get files inside this directory (it
changes based on xdg_config_home) and updated relevant tests.

In ssl.{c,h} I have started work. If they don't exist, the tool now
creates and stores a key and certificate for the CA that this tool will
need to pretend to be. I still need to write tests for this.

.gitignore

@@ -3,3 +3,4 @@
 yaip
 mynotes.md
 *.sqlite
+/certs