deprecated base:test_config.test_complete_file (dup functionality)

plus a little bit of cleaning around (created constants file).
added some notes about inminent deprecation *work in progress*

fix tests by introducing a (dirtish) workaround for
check for openvpn keys during vpn connection initialization.
noted that eipconnection constructor should be better not
having that class of side-effects.

test provider-definition dump functions.

refactored the set-temp-to-home methods to setUpClass
separate provider-fetch tests on different testcases (so they actually
call to requests).

adjusted some loose ends to make tests pass again.
this merge is still half-baked regarding functionality:
I've left in place old Configuration class used by
some tests antialias did on his branch. I plan to merge
that functionality with the more recent JSONConfig
and Spec classes.

Conflicts:
	src/leap/base/configuration.py
	src/leap/eip/config.py
	src/leap/eip/tests/test_config.py

(cherry picked from get-definition.json branch)

solve merge conflict since antialias was working in
a version in which baseconfig was still at `configuration` file.

Conflicts:
	src/leap/base/configuration.py

tests green for load/dump operations on config.
defaults on config spec for LeapServiceProvider should
be outputting a minimal working config for bootstrapping
the connection.

we should be using this config mechanism for other config
operations; but probably we should specify a local_editable flag
for those configs that are only changed by server.

an initial attempt at stablishing base classes
for config. we go with a jsonconfig by now, and
will switch to a different storage backend in near
future.

things will surely be broken at this state;
i'm splitting work on different commits.