Move test samples to reduce setuptools warnings

Previously there are a lot of warning messages of setuptools
in the log files of tox jobs. This is mainly caused by test
samples because these are in python codes directories.

This patch moves test samples from under
{tosca-parser_root}/toscaparser/tests to under
{tosca-parser_root}/samples/tests.

This patch also contains the following changes:
* Removed unused test samples.
* Fixed usage.rst command example.
* Changeing unit tests that reference external URL to use mock
* Mock methods used in unit tests have been made into common methods.

Change-Id: I80ab6ce0b3344f19afb4d16554c799747b1f2567

doc/source/usage.rst

@@ -13,7 +13,7 @@ you can install 0.3.0 or higher PyPI release of TOSCA-Parser as available at the
 https://pypi.python.org/project/tosca-parser and test use the parser via CLI
 entry point as::
 
-    tosca-parser --template-file=toscaparser/tests/data/tosca_helloworld.yaml
+    tosca-parser --template-file=samples/tests/data/tosca_helloworld.yaml
 
 The value to the --template-file is required to be a relative or an absolute path.