Deprecate run_tests.sh

This commit deprecates run_tests.sh script and adds a deprecation
document. We don't pay attention this script actually however, I suppose
new people are coming and see the top of the directory and find this
script and try to use this. And if something wrong happens, we need to
ask and check 'which runner did you use?'. So I would like to reduce the
ways to execute unit tests.

Change-Id: Ia764fa3a15dc9faa753d4aca4c76462a8b9dd40b
diff --git a/run_tests.sh b/run_tests.sh
index 22314b6..a856bb4 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -17,6 +17,44 @@
   echo "  -- [TESTROPTIONS]        After the first '--' you can pass arbitrary arguments to testr "
 }
 
+function deprecation_warning {
+  cat <<EOF
+-------------------------------------------------------------------------
+WARNING: run_tests.sh is deprecated and this script will be removed after
+the Newton release. All tests should be run through testr/ostestr or tox.
+
+To run style checks:
+
+ tox -e pep8
+
+To run python 2.7 unit tests
+
+ tox -e py27
+
+To run unit tests and generate coverage report
+
+ tox -e cover
+
+To run a subset of any of these tests:
+
+ tox -e py27 someregex
+
+ i.e.: tox -e py27 test_servers
+
+Additional tox targets are available in tox.ini. For more information
+see:
+http://docs.openstack.org/project-team-guide/project-setup/python.html
+
+NOTE: if you want to use testr to run tests, you can instead use:
+
+ OS_TEST_PATH=./tempest/tests testr run
+
+Documentation on using testr directly can be found at
+http://testrepository.readthedocs.org/en/latest/MANUAL.html
+-------------------------------------------------------------------------
+EOF
+}
+
 testrargs=""
 just_pep8=0
 venv=${VENV:-.venv}
@@ -32,6 +70,8 @@
 config_file=""
 update=0
 
+deprecation_warning
+
 if ! options=$(getopt -o VNnfuctphd -l virtual-env,no-virtual-env,no-site-packages,force,update,serial,coverage,pep8,help,debug -- "$@")
 then
     # parse error