Add unit tests and automatic quoting

lib/private/appframework/db/db.php

lib/private/db/connection.php

lib/private/db/querybuilder/compositeexpression.php

lib/private/db/querybuilder/expressionbuilder.php

lib/private/db/querybuilder/literal.php

lib/private/db/querybuilder/parameter.php

lib/private/db/querybuilder/querybuilder.php

lib/private/db/querybuilder/queryfunction.php

lib/private/db/querybuilder/quotehelper.php

lib/public/db/querybuilder/icompositeexpression.php

lib/public/db/querybuilder/iexpressionbuilder.php

lib/public/db/querybuilder/iliteral.php

lib/public/db/querybuilder/iparameter.php

lib/public/db/querybuilder/iquerybuilder.php

lib/public/db/querybuilder/iqueryfunction.php

lib/public/idbconnection.php

tests/lib/db/querybuilder/expressionbuildertest.php

tests/lib/db/querybuilder/querybuildertest.php

tests/lib/db/querybuilder/quotehelpertest.php

tests/lib/share/share.php