added basic files to use MySQL as a client.

We will use 'ndo2db' to get Nagios data. ndo2db writes data form
Nagios to MySQL DB. So we first implements a framework for reading
data via MySQL.
implemented a constructor of DBAgentMySQL.
added a call of mysql_close on the destructor.
Fixed the name used in the test.

The database with prefix: test_ can be accessed from any users.
added an instruction that have to been done before the tests of testDBAgentMySQL.
inserted 'Global' to be suitable for its function.

createDBAgent ->
createGlobalDBAgent
added a function automatically to make a test database if it doesn't exist.
extracted test data of testDBAgentSQLite3 to be available from other tests (mainly for testDBAgentMySQL).
implemented DBAgentMySQL::createTable().
fixed the problem that wrongly passes an assertion, which was written by mistake.
implemented  DBAgentMySQL::insert().
added a template test function that can be used both from testDBAgentMySQL and testDBAgentSQLite3.
rewrited a test with the DBAgentChecker test framework.
added strict checks for a test of created table.
rewrited testDBAgentMySQL::test_insert() with a DBAgent test framework.
rewrited testDBAgentSQLite3::test_insert() with a DBAgent test framework.
rewrited test_insertUint64_0x7fffffffffffffff() with a DBAgent test framework.
rewrited test_insertUint64_0x8000000000000000() with a DBAgent test framework.
rewrited test_insertUint64_0xffffffffffffffff() with a DBAgent test framework.
cleaned up test_insertUint64 tests with the parameterized template functions.