Fixing a bug in reading snappy-compressed text that spans multiple scan ranges.

It was missing handling of files with SNAPPY_BLOCKED compression type.

Change-Id: I5e19200914559cf85337fb5a60a2d0906d4aefa7
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3700
Reviewed-by: Ippokratis Pandis <ipandis@cloudera.com>
Tested-by: jenkins
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3753