[DBAgentTest] Clean up.
[DBAgentTest] Create indexes of the tables for test.

Some tests such as dbAgentTestUpsert() need indexes.
Actually dbAgentTestUpsert() only uses the privmary key that
is also created when the creation of tables.
So no serious problems is currently caused.
[DBAgentMySQL] Fix a problem that updates a primary key on upsert.
[DBAgentMySQL] Clean up insert().
[DBAgentTest] Add a column that has a unique index for future test.

This patch itself doesn't add a new kind of test.
[DBAgentSQLite3] Fix the problem that doesn't keep the auto incremented value.

When the record with a unique key is upserted and it's duplicated,
we want to keep the value in the primary key's column. However,
the previous implementation with AUTO_INCREMENT_VALUE doesn't do so.
[DBAgentTest] Prepare to fix dbAgentTestUpsertWithPrimaryKeyAutoInc().

dbAgentTestUpsertWithPrimaryKeyAutoInc() checks that a value in
column with the primary key is kept. However, the target table:
COLUMN_DEF_TEST doesn't have the flag: SQL_COLUMN_FLAG_AUTO_INC.

This patch is a preparaton of the fix in which
dbAgentTestUpsertWithPrimaryKeyAutoInc() uses COLUMN_DEF_TEST_AUTO_INC.
[DBAgentTest] Use a test table that has SQL_COLUMN_FLAG_AUTO_INC.
[DBAgent] Add UpdateArg::add(const size_t &, const ItemGroup *).
[DBAgentSQLite3] Clean up.
[DBAgentSQLite3] Fix a build error on TravisCI.
[DBAgentTest] Suppress a waring due to a missing of a space.

In C++11 mode, the following warning is shown.

DBAgentTest.cc:949:36: warning: invalid suffix on literal; C++11 requires a space between literal and identifier [-Wliteral-suffix]
     dbAgent, checker, val, sprintf("hanako.%"PRIu64, id).c_str());
[DBAgentTest] Fix the build error after the rebase.
[DBAgentSQLite3] Fix 'update' without the condition.

The previous version doesn't add the condition when an update statement
for an upsert.
[DBAgentMySQL] Use SeparatorInjector instead of SeparatorInserter.

SeparatorInserter was deleted becaise it is a temporary
implementation and no longer used.
[DBAgentSQLite3] Remove a needless space
[DBAgent] Rename isValueAutoIncrement() to improve readability.

isValueAutoIncrement ->
isAutoIncrementValue ->

The corresponding constants are AUTO_INCREMENT_VALUE(_64). So the
similar names make it easy to understand their relation.
[DBAgent] Remove an unused parameter of isAutoIncrementValue().
[DBAgentTest] Fix a build error due to the remove of ColumnDef::tableName.
[testDBAgent] Use an unabbreviated name for readability.