Fixes #909 - Move the exception on lock acquisition failure from checkout to outside of the try-catch block so that subsequent threads do not clear the lock set by the first thread
Enhance docs for most framework processors for #581
#910 - Added overloaded methods in CustomerDao and CustomerService to prevent caching the query to get customer username
Merge branch 'BroadleafCommerce-3.1.x' into develop

Conflicts:
	core/broadleaf-framework-web/src/main/java/org/broadleafcommerce/core/web/processor/AddSortLinkProcessor.java