Fixed bug in bq_get and bq_post that generated incorrect json requests
by changing the config variable from a list to a config
Modified the list_tabledata() function to match BQ API change.
Now when there are no more pages to be read from a job, the
server no longer returns a page token.
Merge pull request #5 from jhyrkas/api_change

Modified the list_tabledata() function to match BQ API change.
Got rid of httr::config() in parameters. For some reason setting config = config()
throws a recursion error, so config is defaulted to NULL and assigned to config()
if NULL in method body.
Merge pull request #3 from jhyrkas/json

Incorrect JSON generated in query_exec