Default configuration tox env name change

Currently tox configuration has env by name "custom", renaming it
to "default" to generalize for all supported system.

Going forward there will be no system model concept supported from
the test env or from developement skeleton model.

Resolves #645

Change-Id: I0b678ffc10e373214bd1dec425182462955acb2c
Signed-off-by: George Keishing <gkeishin@in.ibm.com>

README.md

@@ -74,7 +74,10 @@ Run tests
 How to test individual test
 ```shell
     One specific test
-    $ tox -e custom -- -t '"DIMM0 no fault"' tests/test_sensors.robot
+    $ tox -e default -- -t '"DIMM0 no fault"' tests/test_sensors.robot
+
+    No preset environment variables, default configuration for all supported systems.
+    $ OPENBMC_HOST=x.x.x.x tox -e default -- tests
 
     No preset environment variables, one test case from one test suite
     $ OPENBMC_HOST=x.x.x.x tox -e barreleye -- -t '"DIMM0 no fault"' tests/test_sensors.robot

tox.ini

@@ -19,7 +19,7 @@ commands =
     cp bin/ssh_pw {envdir}/bin/ssh_pw
 
 
-[testenv:custom]
+[testenv:default]
 deps = {[testenv]deps}
 setenv = {[testenv]setenv}
 commands =