* cherry pick from develop branch.

* fix conflict and reformat by autopep8.

add getVariable() to util/sql.py

add 4 testcases to query/queryWildcardLength.py

add query/queryTbnameUpperLower.py

add util/common.py for adding common function in case of duplicate use

fix a small-probability bug for insert/schemalessInsert.py

finish 40 cases for schemaless in insert/schemalessInsert.py, but 5 of them could not be used now because multiThreading is not complete

modify util/sql.py: add row_tag in query(), add col_tag in getColNameList(), add checkEqual() and checkNotEqual()

add insert/schemalessInsert.py to fulltest.sh