[WIP] ir.ui.view's arch field fetches disk version if --dev mode is used
[FIX] stored arch field is now arch_db
[FIX] register dev_mode command line switch
[FIX] Temporary disable addons subcommand auto discovery

The problem with the current approach is that it imports all modules in
order to discover which one exposes a subcommand by subclassing
openerp.cli.Command. At that time, the arguments are not parsed in order
to setup the config because a subcommand could potentialy alter the
command line arguments (which is the case of `start`)

This behavior causes the modules to be imported with the default config and all
the modules using some config keys at startup won't have to value they
are supposed to have when considering the shared command line switches.

Long story short:

$ odoo --workers=6

is ok, but

$ odoo start --workers=6

is not.

As the automatic subcommands are not used yet, we temporary disable it
until as proper solution is found.
[ADD] @conditional decorator for a conditionally applied decorator
[IMP] Make read_template conditionally cached (--dev)
[ADD] web_tip: module for tip definition and display

Also added with this commit:
crm: tip data
web: hooks (events) for web_tip
web_kanban: hooks (events) for web_tip
[IMP] Store relative path in arch_fs
[IMP] change arch_fs's type to field.char
Merge pull request #1625 from odoo-dev/master-views-arch-on-disk-fme

[MERGE] Read ir.ui.view's arch from disk in development mode

A new switch named `--dev` has been added to the openerp.cli's arguments.

This development mode's purpose is to activate some specific behaviours in order to ease development.

For the moment, the only effect of `--dev` is to make the ir.ui.view's arch function field read the data from the original xml file (if any), allowing the developer to change a view and check the effect without having to update it's database.

This feature will currently work only with existing views. If you add a view you still have to update your database.
[IMP] tour: add a tour to click on all menu items, sub menu items, need action, and views