[FIX] tools: find_in_path: config is not ready at import time

commit f76d4525a was not actually working: extra keys from
config files are not yet into the config options dict at
import time. The fix is to move the logic inside the method,
like in `find_pg_tool` just below.

Also fix the use of `find_in_path` in report.py: the subprocess
may also raise AttributeError exception, so instead of listing
all the possible ones just re-raise the IOError shallowed by
`find_in_path` when the result is None.

Fixes #3809 #3811
[ADD] ws doc: introspection, reports and workflows

* use static imports in java examples to make them terser
* inline ``domain`` in java and php example to make examples more
  self-contained
* try to extend/improve Model.write's docstring
* add convenience kwarg to fields_get, mostly for user-driven
  introspection

Closes #3689
[CHG] doc: company officially renamed
[FIX] yet another filter fix... (crm reporting)

Same problem as before: filters do not compose properly with the implicit
'&', and they are filtering on the wrong model (should filter on probability
in the crm.case.stage model and not on the crm.opportunity.report)
[FIX] doc/backend: typos in example code
[FIX] im_chat: unlink im chat presence on user deletion

It wasn't possible to delete a user if he had a im chat presence linked to him.
[REF] mail: extract auto subscribe notifications sending into a sub-method

To allow customization, such as do not send the notification to the partner that subscribed himself to the thread (he probably already read the thread, no need to send him an email)
[IMP] http: do not log traceback for Warnings
[IMP] Show product_uom_qty instead of normalized quantity in mrp order report