Remove ruamel.yaml dependency, use pyyaml instead

Change-Id: Ifb51246e4f920f4e1ef98e1d8393ea93cf4e64e0
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/setup.py b/setup.py
index 2140468..7c6ad39 100644
--- a/setup.py
+++ b/setup.py
@@ -29,8 +29,7 @@
     license='Apache 2',
     install_requires=[
         'Click', 'prettytable', 'pyyaml', 'pycurl', 'python-magic',
-        'jinja2', 'osm-im', 'verboselogs', 'packaging', 'ruamel.yaml',
-        'requests',
+        'jinja2', 'osm-im', 'verboselogs', 'packaging', 'requests',
         'osm-im @ git+https://osm.etsi.org/gerrit/osm/IM.git#egg=osm-im',
     ],
     setup_requires=['setuptools-version-command'],