Add dependencies for the REST API client (#92)

* Add dependencies for the REST API client

* Add pyOpenSSL for Python 2.7.x

setup.py

@@ -32,9 +32,11 @@ def check_setuptools():
 traces to your Instana dashboard.",
       zip_safe=False,
       install_requires=['autowrapt>=1.0',
+                        'basictracer>=3.0.0',
+                        'certifi>=2018.4.16',
                         'fysom>=2.1.2',
                         'opentracing>=2.0.0',
-                        'basictracer>=3.0.0'],
+                        'urllib3>=1.18.1'],
       entry_points={
                     'instana':  ['string = instana:load'],
                     'flask':    ['flask = instana.flaskana:hook'],
@@ -49,6 +51,7 @@ def check_setuptools():
             'flask>=0.12.2',
             'lxml>=3.4',
             'MySQL-python>=1.2.5;python_version<="2.7"',
+            'pyOpenSSL>=16.1.0;python_version<="2.7"',
             'requests>=2.17.1',
             'urllib3[secure]>=1.15',
             'spyne>=2.9',