Fix app.config argument passing when using ct_run

ct_run has changed its config key from -ct_config to -config,
thus, -config key, used to specify app.config now must be
placed after -erl_args
Merge branch 'ct_appconfig_fix' of https://github.com/kittee/rebar into kittee-ct_appconfig_fix

Conflicts:
	THANKS
Merge branch 'kittee-ct_appconfig_fix'