Checks for 'dict' in `x.__class__.__name__` b/c
neither `type()` nor `isinstance()` is available.

!!   Not tested with an actual   !!
 !!  configured `ext_pillar` yet  !!

- jinja on RHEL/CentOS 6 has no 'mapping'
  test (see salt-formula issue #193)
- {% do ... %} allows no assignment, only
  function calls
- of course, `type(foo) is dict` doesn't
  work because it's no jinja test
- maybe `.isinstance()` would be nicer/more
  reliable

Some vars were missing {{ }}
Indentation was broken
isinstance is not available in Salt

Using the old salt.engines pillar and merging it with the new
salt.[master|minion].engines pillar.
This way, it doesn't break previous behavior and permits to define
common engines on master and minion.
In the merge, the salt.[master|minion].engines pillar takes precedence
if conflict as it's the more specific pillar.

the engines are now configured using the following pillars:

* salt.master.engines
* salt.minion.engines

instead of a global salt.engines pillar.

Note: the pillar.example provided seems to assume this behaviour.
(the pillar is salt.master.engines.slack and not salt.engines.slack)

Signed-off-by: Rene Jochum <rene@jochums.at>

Signed-off-by: Rene Jochum <rene@jochums.at>

This avoids problems when values are strings containing colons. And it
mimicks what was already done for the salt-minion's configuration file.

Fixes #233.