Some formatting corrections, moved config and db with in the new Markovirc class, wrapped postgres execute.

 * Added a new config option for postgres database name
 * Reorganized include order in the main bot file
 * $set => bot.set
 * $db => bot.db, exec now a function for bot which uses sqlite3 syntax
 * Markovirc class now extends Cinch and implements the two variables above + exec
 * bot is now a global, $bot