Reverted to old method of api_key input

It worked just fine, and still preserved security.

Author: bmschwartz

test/verifications.py

@@ -5,14 +5,11 @@
 import unittest
 import os, sys
 
-blockscore.api_key = 'your_api_key'
-
 class TestBlockscore(unittest.TestCase):
 
     def setUp(self):
         try:
-            api_key = blockscore.api_key
-            self.client = blockscore.Client({'api_key':api_key})
+            self.client = blockscore.Client({'api_key': 'your_api_key'})
         except KeyError:
             sys.stderr.write("To run tests, you must have a BLOCKSCORE_API environment variable with a test api key\n")
             sys.exit(2)