Refactored constants

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@181170 a5903396-d722-0410-b921-86c7d4935375
Fixing https://wso2.org/jira/browse/WSAS-1483 - when web.xml of webapp has enable.statistic parameter, bam configurations should be accordingly.

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@181172 a5903396-d722-0410-b921-86c7d4935375