Description of problem:

Unable to add amazon provider, It fails with following error. 

Credential validation was not successful: Unexpected response returned from system: undefined local variable or method `http_proxy_uri' for #


Version-Release number of selected component (if applicable):
 Version 5.7.0.3.20160927165516_075d0f3 

How reproducible:
Always

Steps to Reproduce:
1. Add amazon provider, Enter Access Key ID
   and Secret Access Key and hit on validate 
   button. 

Actual results:
Failure in validation 

Credential validation was not successful: Unexpected response returned from system: undefined local variable or method `http_proxy_uri' for #

Expected results:
Validation should work. 

Additional info:

[----] W, [2016-10-06T06:04:01.060702 #3038:1835e54]  WARN -- : MIQ(ManageIQ::Providers::Amazon::CloudManager#authentication_check_no_validation) type: ["default"] for [] [cfme] Validation failed: error, Unexpected response returned from system: undefined local variable or method `http_proxy_uri' for #<ManageIQ::Providers::Amazon::CloudManager:0x00000013783080>
[----] E, [2016-10-06T06:04:01.060937 #3038:1835e54] ERROR -- : MIQ(ems_cloud_controller-create): Credential validation was not successful: Unexpected response returned from system: undefined local variable or method `http_proxy_uri' for #<ManageIQ::Providers::Amazon::CloudManager:0x00000013783080>