roles/dspace: Increase Tomcat connector's maxHttpHeaderSize

In DSpace configurations where there a user has many permissions,
either inherited from a group or assigned directly to the user, the
size of the Solr query for many XMLUI Discovery actions becomes too
large and causes an error. Increasing the maxHttpHeaderSize allows
these queries to work properly (default is 8192, ie 8KB).

This error is caused by the access rights awareness functionality
that is enabled by default on DSpace 4, 5, and 6. There are many
discussions about errors caused by this on the dspace-tech mailing
list.

See: http://tomcat.apache.org/tomcat-7.0-doc/config/http.html
See: https://wiki.duraspace.org/display/DSDOC5x/Discovery#Discovery-AccessRightsAwareness

roles/dspace/templates/tomcat/server-tomcat7.xml.j2

@@ -73,7 +73,8 @@
     <Connector port="8081" protocol="HTTP/1.1"
                connectionTimeout="20000"
                address="127.0.0.1"
-               URIEncoding="UTF-8" />
+               URIEncoding="UTF-8"
+               maxHttpHeaderSize="16384" />
 
    <!-- tell tomcat it's being proxied via 443 / scheme https -->
     <Connector port="8443" protocol="HTTP/1.1"