Description of problem:
Attempting to register a system with an activation key fails due to the current user not being set properly.

Version-Release number of selected component (if applicable):
SE 1.0.1

How reproducible:
Always

Steps to Reproduce:
1. Create an Activation Key
2. Apply a subscription to the activation key
3. Using a client system properly configured, attempt to register using the activation key
  
Actual results:
Client system will receive an error: "Error updating system data, see /var/log/rhsm/rhsm.log for more details." 

And the /var/log/rhsm/rhsm.log will show: 
2012-08-13 14:40:19,793 [ERROR]  @cache.py:164 - Error updating system data
2012-08-13 14:40:19,793 [ERROR]  @cache.py:165 - Invalid credentials

Expected results:
The system should be registered appropriately or receive an error message that reflects the current state of the subscriptions attached to the Activation Key. 
For example, "Multi-entitlement not supported for pool with id"

Additional info:
This appears largely due to a chicken and egg problem whereby the current user is not properly set when attempting to look up activation keys when a client registers using an activation key.