Merge pull request #137 from mattgilbert/scalarList-allowNullValues

executeScalarList() returns partial list when there are nulls
Simplified AbstractCache class by removing the use of ThreadLocal. This
should fix #138
Fixes #139
Moved closing of statements to quirks. By default, Sql2o will no longer call statement.isClosed before calling statement.close() method.
Fixes #140
Moved Jndi logic to another class, to avoid importing javax.naming.* classes in Sql2o.java. Fixes support for Android.
Merge branch 'release-1.5.x'