Treat Twitter tokens as sensitive values in GetTwitter

The GetTwitter processor marks properties Consumer Secret and Access Token Secret as sensitive, but Consumer Key and Access Token are not marked as such. The Twitter API documentation says:

Your applications’ API keys should be guarded very closely. They represent your unique access to the API and if leaked/used by other parties, this could lead to abuse and restrictions placed on your application. User access tokens are even more sensitive. When access tokens are generated, the user they represent is trusting your application to keep them secure. If the security of both API keys and user access tokens are compromised, your application would potentially expose access to private information and account functionality.

Once the processor code is updated to treat these properties as sensitive, there may need to be backward-compatibility changes added to ensure that existing flows and templates do not break when deployed on the "new" system (following, marked as 1.X). The following scenarios should be tested:

• 1.8.0 flow (unencrypted CK and AT) deployed on 1.X
• 1.8.0 template (unencrypted CK and AT) deployed on 1.X
• 1.X flow (encrypted CK and AT) deployed on 1.X
• 1.X template (no CK and AT) deployed on 1.X

The component documentation should also be appropriately updated to note that a 1.X flow (encrypted CK and AT) will not work (immediately) on a <=1.8.0 instance. Rather, manual intervention will be required to re-enter the Consumer Key and Access Token, as the processor will attempt to use the raw value

 enc{ABCDEF...} 

from the flow.xml.gz file as the literal CK and AT.