Donald Trump, the billionaire businessman and GOP presidential frontrunner, has taken off the gloves in his fight with Texas Sen. Ted Cruz. What was friendly jabbing in the Fox Business Channel debate has gotten nasty as Trump now directly questions Cruz's eligibility to serve as president and the $1 million loan Cruz took from Goldman Sachs to jumpstart his Senate campaign. "Goldman Sachs owns him, he will do anything they demand. Not much of a reformer!" Trump tweeted. "Ted Cruz purposely, and illegally, did not list on his personal disclosure form personally guaranteed loans from banks," Trump added. "They own...