Revert "#12 add factory_girl gem setting"

factory_girlは複雑さを増すだけなので削除

This reverts commit 0cc76e98af067ea9f8e8aa12f6d5bfc681c711ef.
Revert "#12 add gems for test"

factory_girlはテストを複雑にしすぎてしまうので削除
This reverts commit 3b320c187b1e2aa72670c306b38ed3824207b208.