Add nice interactive html representation of the agent's state machine

This patch adds a script that can autogenerate html file that
makes it easier to investigate the state transitions in hosted
engine's FSM.

Hovering your mouse above one of the states at the edge of the
circular diagram hides all transitions that are not relevant to
that state.

The html file can be autogenerated using the same command that
is used to prepare the graphviz version:

make fsm

Change-Id: I82c72d044818c8412a2517a4431aecf8412add7d
Signed-off-by: Martin Sivak <msivak@redhat.com>