Renamed 'canOpen' as 'probeContent'. As a side-effect, this change allow us to restore
the 'canOpen' method that existed in SIS 0.3 as a deprecated method, to be removed in
SIS 0.5. Note that SIS 0.3 javadoc clearly stated that the 'canOpen' method was going
to change.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1514744 13f79535-47bb-0310-9956-ffa450edef68