Table-specific split policy for salted tables:

Added a table-specific split policy when we are creating salted
tables. Also added a max file size for salted tables, if the max file
size split policy is used. Both split policy and max file size are
controlled via 2 new CQDs:

  HBASE_SALTED_TABLE_MAX_FILE_SIZE (default: 0 - Use HBase default (10 GB))
  HBASE_SALTED_TABLE_SET_SPLIT_POLICY  (default: ON)
   - ON means that salted tables will use ConstantSizeRegionSplitPolicy.
   - OFF means that tables (salted or not) will use the default HBase split
     policy, unless specified in the HBASE_OPTIONS clause.

Examples:

CREATE TABLE T ... SALT ...

  - Uses ConstantSizeRegionSplitPolicy with the default max file size
    (10 GB unless changed in hbase-site.xml)

CREATE TABLE T ... <no salt option>

  - Uses the default HBase split policy
    (IncreasingToUpperBoundRegionSplitPolicy, unless changed in
    hbase-site.xml). I’ll work with Marvin to stop changing this
    default in our installer.

CREATE TABLE T ... SALT ... HBASE_OPTIONS (SPLIT_POLICY =
   'org.apache.hadoop.hbase.regionserver.IncreasingToUpperBoundRegionSplitPolicy');

  - Uses IncreasingToUpperBoundRegionSplitPolicy, overriding the CQD

CQD HBASE_SALTED_TABLE_SET_SPLIT_POLICY OFF;
CREATE TABLE T ... SALT ...

  - Uses the default HBase split policy

Change-Id: I4e221479e2c05c97d69b4865fefffba7e3e561fe