LOS ANGELES, Jan. 17 (Xinhua) -- Senator Barack Obama, vying for the Democratic presidential candidacy, vowed to change bankruptcy laws and cap interest rates during his campaign tour in Southern California, the Los Angeles Times reported Thursday. During what his campaign dubbed a "Roundtable on Economic Opportunity" there, Obama called for an exemption in the 2005 bankruptcy bill for people who can persuade a bankruptcy court that they filed for bankruptcy because of debts caused by medical expenses. His proposal also includes extending the 36-percent limit on payday loans to military members to all Americans; encouraging banks, credit unions and...