NpgsqlParameterCollection

Add some AddWithValue() functions.
Updated comments on Add(string, object) to be more obviously obsolete.
Quieter again.
Merge pull request #48 from glenebob/gitignore

Gitignore update since @roji's tests work
Merge pull request #47 from glenebob/parameter_functions

NpgsqlParameterCollection
Merge branch 'master' of https://github.com/franciscojunior/Npgsql2 into binary_backend_format