Kim Kyung-Hoon/ReutersTOKYO (Reuters) - Japan's lower house was dissolved on Thursday ahead of an expected snap Oct. 22 election being called by Prime Minister Shinzo Abe, as he seeks to confirm his mandate in the face a rising challenge from a popular new conservative party. Abe, a conservative who returned to power in 2012, is hoping a boost in his voter support in recent months will help his Liberal Democratic Party-led (LDP) coalition maintain a simple majority.