Investigate if JDBC fetch size can improve performance in some situations

[Nicklas Nordborg]

For MySQL the JDBC fetch size is set by the defaultFetchSize parameter in the connection url. The current value is 100 which may not be optimal. During testing of the migration (#1630) we discovered that increasing the fetch size can improve the performance a lot.

The default fetch size we use now is good enough for most table listings, etc. since we seldom load more items on one page. It may not be good enough for analysis plug-ins that load complete bioassay set data. We might even be able to improve experiment explorer a bit more....