Generate some static contents to display the graph

Now the .dot file is exported under <path>/dump/graph.dot and is used
by dump/index.html to draw a nice graph. There is no string/script
embedding into OCaml code, so it's easier to hack/improve if needed:
the static contents now lives in `lib/server/static`
Display more information on commit nodes in the graph
Update the dump graph every second

with some nice transitions between two graph updates

wow!
Generate proper HTML nodes in the dumped graph

Now we can tune the output more easily (eg. using CSS)
Start applying some CSS rules
Re-emable (active) live update
Support display of bounded-depth graph (by default, depth=4)

This make it possible to display normal Git repo

to change the default depth, connect to http:/localhost:8080/dump&depth=xx
You can also add 'reload=false' if you don't want the page to auto-reload every seconde.
Add a hackish way to connect to a remote Git repo

Need to integrate that properly at one point
Create an IrminStore.S signature

Would be good to not expose the the IrminBranch.S sig at one point
(but that means that we don't have access to the block and tag stores
anymore).
Fix more weird OCamlGraph outputs
Add some colors to the graph JS output
Add an intrusion example
Add a process example
Merge pull request #61 from samoht/cleaner-graphs

Cleaner graphs