fix: set last_created_at data from tweet_status.txt at the first starting time
get query result for forward searching with since_id

implemented getting query result for forward searching with since_id
so that we can use search methods for back and forth
merge two different search methods to be simplified to use it

Don't need to two different search methods, since they had almost same
code without 2 lines.
easy to add item to query through rewriting crawlingtweets

Change the structure for crawling tweets to add item easier
Thanks to eungju.park