[IMP] http move db dispatching on the orm level
Split low level dispatching and high level dispatching.
Low level dispatching is used when the db is unknown it's only used by a few
controller in base and web.
High level dispatching is used when the db is known, it is used by most
controllers and it handles authentication and errors. Because it's a regular
osv object all it is fully overridable by openerp modules.
[IMP] model converters for routes, to directly get the browse record
example @route(['/job/detail/<model("hr.job"):job>'], type='http', auth="user")
[FIX] use AbstractModel, use session.db to ir_http dispatch for none controllers
[IMP] ir_http better exception handling for http errors
[FIX] http.py use checked_call for concurrency retry and exception handling
[FIX] make routing converters modular
[IMP] http move db dispatching to AbstractModel ir.http

Allow module to override the http dispatching process:
- The default implementation uses werkzeug.routing but any other method could
  be used, it'a also possible to pre/postprocess (i.e. url aliases)
- Authentication (auth param on route) is plugggable by defining now
  _auth_method_<methodname>
- Error handler are overridable, any module can define a new exception and
  handle it by orverriding the _handle_<error_code> method.
- Add model converters for routes, to directly get the browse record example
  @route(['/job/detail/<model("hr.job"):job>'], type='http', auth="user")

This is done by splitting dispatching, when the db is unknown low level http.py
dispatching is used, it's only used by a few controller in base and web. When
the db is known, ir_http is used because it's a regular Model it is fully
overridable by openerp modules.