People/rporres/sqlite autoincrement

As stated in the SQLite docs, the behaviour of autoincrement changes when the column is a primary key.

http://www.sqlite.org/autoinc.html

Heres a summary of the changes included:

- I have patched SQL::Translator::Generator::DDL::SQLite to add the word AUTOINCREMENT to the primary keys column is detected as primary key.
- I've also patched 30sqlt-new-diff-sqlite.t and 48xml-to-sqlite.t as the new Generator broke some of the tests
- I've added a couple of tests in 56-sqlite-producer.t to prove the new feature.
- I've added my name and mail in the AUTHORS file as suggested by a Peter Rabbitson message in sqlfairy-developers mailing list

Please do take into account that I'm very new to SQL::Translator and I don't know if the changes and the implementation of them are in sync with the common practices of SQL::Translation.

Regards,

Rafa

PS. BTW, thanks for SQL::Translator. It's been __VERY__ helpful ;-)