Move BuildData.java to src/tools

This change addresses #268 comments by moving `BuildData.java` into src/tools and making it one of `tsdb`'s command classes. 
```
oozie@number5:/usr/share/opentsdb/bin$ ./tsdb version
net.opentsdb.tools 2.1.0 built at revision bbe7925 (MODIFIED)
Built on 2014/09/14 01:14:57 +0000 by oozie@anonymous:/home/oozie/src/opentsdb/build

oozie@number5:/tmp$ wget -qO- localhost:4242/version
net.opentsdb.tools 2.1.0 built at revision bbe7925 (MODIFIED)
Built on 2014/09/14 01:14:57 +0000 by oozie@anonymous:/home/oozie/src/opentsdb/build
```

BONUS: This change will simplify the eclipse setup procedure by taking out the "copy BuildData.java" bullet point.
http://opentsdb.net/docs/build/html/development/development.html