bio-formats: Add joda-time to build dependencies
MetamorphReader: Use joda-time
Add joda-time dependency to autogen, scifio and specification
autogen: VelocityTools uses joda-time
DateTools: Use joda-time in place of Date and SimpleDateFormat

Also add utility functions getTimestamp and getFileTimestamp to
replace existing timestamp string functions.
loci-plugins: ConfigWindow uses DateTools.getTimestamp
scifio: JavaWriter uses DateTools.getTimestamp
test-suite: Use DateTools.getFileTimestamp
TestTools: Remove extra '-' in log filename
ome-xml: Timestamp.valueOf returns null on null input
scifio-devel: DateTools catches exceptions and logs parse errors
bio-formats: PrairieReader uses Timestamp.valueOf

This avoids dealing with exceptions on parse errors.