Also fixed a few errors like the time it takes to install,
some references to NOX, etc..

Left in noxcore ref, since you can still install it.

Thanks to @xdhanz for the catch, and pull request
closes #84

We may want to start cutting things at some point - it looks more
complicated than it really is!

Added alpha releas comments, inc. do not distribute yet.

Added install notes for install.sh.

Before this commit, you'd have to manually insert the kernel module for
OVS or OF kernel modules, and you couldn't run one regression test with
all 3.

Now, these are kmod insert/remove is handled automatically.

Simplifies installation step

Now, to reference mininet files, use 'import mininet.mininet'.

PYTHONPATH mods are no longer required for installation.