[setup.py] Update dependenices (sonic-net#120)

Update dependencies in setup.py to align with current needs. This allows for implicit installation of dependencies at build and run time, and prevents the need to explicitly install these packages.

setup.py

@@ -24,9 +24,18 @@
         'sonic_sfp',
         'sonic_thermal',
     ],
+    # NOTE: Install also depends on sonic-config-engine for portconfig.py, but we are not yet
+    # building a Python 3 version of sonic-config-engine. Also, this dependency should be
+    # eliminated by moving portconfig.py functionality into sonic-py-common
     install_requires=[
+        'natsort==6.2.1', # 6.2.1 is the last version which supports Python 2
+        'PyYAML',
+        'redis',
         'sonic-py-common'
     ],
+    setup_requires= [
+        'wheel'
+    ],
     classifiers=[
         'Development Status :: 3 - Alpha',
         'Environment :: Plugins',
@@ -37,7 +46,7 @@
         'Natural Language :: English',
         'Operating System :: POSIX :: Linux',
         'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Topic :: Utilities',
     ],
     keywords='sonic SONiC platform hardware interface api API'