ant build script

[Xueming Shen]

Hi,

This change is to add the ant build script/nb project to the make 
directory. It
supports build, test, clean and jar now, in which I believe is enough 
for now.
It should be easy to add the coverage back, if we have the updated 
ÅllTest in
test repository, but I doubt the necessity. With this change you can now 
open
the threeten project in a nb against a jdk8_thrreeten repository and work on
the threeten stuff without building the whole jdk8/jdk repository.

A workaround has been added into TzdbZoneRulesProvider to read the 
tzdb.jar from
location specified by a property -Djavax.time.zone.tzdbjar=..., so the 
TestNG tests
can be run separately on a jdk runtime that does not have the threeten 
stuff.

Please help take a look. If it's fine with you guys, I will push it in.

http://cr.openjdk.java.net/~sherman/jdk8_threeten/antbuild/webrev/

Thanks
-Sherman