Make `tempest init` working dir an abspath

The working directory can be either a relative path or absolute path
depending on how `tempest init` is called. If `tempest init` is called,
the working directory is absolute, but if `tempest init [dir]` is
called, the working directory is relative. The relative case leads to a
bug in setting up the tempest config file later.

We normalized and absolutized local_dir early on, and make everything
work with abspath. This minimize handling of the different paths and
reduces the chances of bugs from handling in later code.

Change-Id: I6dc314017eb264302ba68bbf25060e833d8e317a
Closes-Bug: #1593747
diff --git a/tempest/cmd/init.py b/tempest/cmd/init.py
index 77d62d3..b9db989 100644
--- a/tempest/cmd/init.py
+++ b/tempest/cmd/init.py
@@ -138,6 +138,8 @@
                         "config dir %s can't be found" % config_dir)
 
     def create_working_dir(self, local_dir, config_dir):
+        # make sure we are working with abspath however tempest init is called
+        local_dir = os.path.abspath(local_dir)
         # Create local dir if missing
         if not os.path.isdir(local_dir):
             LOG.debug('Creating local working dir: %s' % local_dir)