misc: added script to fix app.conf

This script renames app.conf to app.yaml, and adapt the yaml structure.

Related to #363.
app: change app.conf structure

Here is the new structure:

  hooks:
    pre-restart:
      - echo abc
      - restarting
    post-restart:
      - do something
      - stupid

Related to #363.
app: rename app.conf to app.yaml

Related to #363.
cmd/tsuru/doc: change app.conf to app.yaml
app: rename loadHooks method to loadConf

Related to #363.
docs/apps/client/usage: fix app.yaml references

The name of the file has changed, along with its format.

Related to #363.
docs/quickstart/python: update page

Mentioning app.yaml, and also update some commands output.

Closes #363.