Jian Xu 3bdd750982 Use FastDateFormat for thread safety ...

Use FastDateFormat for thread safety, this is to fix an exception when a
job is used to ingest multiple tables.  An example exception:
```
Caused by: java.lang.NumberFormatException: multiple points
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1890)
        at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
        at java.lang.Double.parseDouble(Double.java:538)
        at java.text.DigitList.getDouble(DigitList.java:169)
        at java.text.DecimalFormat.parse(DecimalFormat.java:2056)
        at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1867)
        at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1514)
        at java.text.DateFormat.parse(DateFormat.java:364)
        at com.uber.hoodie.HoodieWriteClient.commit(HoodieWriteClient.java:442)
```

2018-02-12 11:43:57 -08:00

..

main

Use FastDateFormat for thread safety

2018-02-12 11:43:57 -08:00

test

Fixing Rollback for compaction/commit operation, added check for null commit

2018-02-06 16:55:23 -08:00