DRILL-4690: initial support for CORS
Added CrossOriginFilter to WebServer based on option HTTP_ENABLE_CORS
Fixed issues related to style
Restricted headers, added run of filterChain
Filter from org.eclipse.jetty.servlets
Enabled configuration, jetty version 9.1.5, restrict filtered paths
CORS by default disabled, reduced size of dependencies (reset maxsize)
This closes #507
