aditya kishore <> in drill

MD-272: Incorporate DRILL-2848 (option to disable decimal data type)

DRILL-2826: Simplify and centralize Operator cleanup

MD-245: Optiq is now Calcite.

MD-192: CONVERT_FROM in where clause

* Set the writeIndex of ByteBuf returned by Unpooled.wrappedBuffer() to 0.

MD-131: Queries fail when using maprdb plugin

MD-125: Update HBase storage plugin to support HBase 0.98

DRILL-1900: Fix numeric overflow problem in HBase stats calculation.

Added link to my talk at Portland Big Data User Group.

+ Corrected base URL for Apache GitHub pages (_config.yml).

+ Updated Drill's GitHub URL (menu.html).

+ Spelling fixes.

+ CRLF => LF, trimmed trailing space.

+ Fixed extraneous DIV tags (overview.html).

+ Removed TABS, restructured nested element with 2 spaces.