BUG: isolated Python3 depedency to the marketplace

etc/python2.7-environment.yml

@@ -23,7 +23,9 @@ dependencies:
   - bottleneck==1.2.1
   - chardet==3.0.4
   - ccxt==1.10.1094
-  - web3==4.0.0b7
+# The Enigma Data Marketplace requires Python3 because it depends on
+# web3, which requires Python3, as building its dependencies breaks in Python2
+#  - web3==4.0.0b7
   - requests-toolbelt==0.8.0
   - click==6.7
   - contextlib2==0.5.5

etc/requirements.txt

@@ -84,5 +84,5 @@ tables==3.3.0
 ccxt==1.10.1094
 boto3==1.4.8
 redo==1.6
-web3==4.0.0b11
+web3==4.0.0b11; python_version > '3.4'
 requests-toolbelt==0.8.0

etc/requirements_marketplace.txt

@@ -1,2 +0,0 @@
-web3==4.0.0b7
-requests-toolbelt==0.8.0