Change Table add/update record method return value.

Return the affected key id. If failed to insert, return 0.
The boolean result of these two function not change. But contains more
meaning.
Enable easySQLite test in GYP.

Run ./build_gyp in root directory can "generate your project".
Test executable is in one of the easysqlite project's target (another
one is easySQLite library).

Test result is good, 1 failed out of 21 tests. Same as the original
code.