Hawaii business executives Chris Eldridge, who founded Hawaii's largest mattress supplier and is a partner in a local biofuel project, and Dustin Sellers, who was co-president of one of Hawaii's largest HR services provider, are moving from the operational side of business and getting into investments. Eldridge and Sellers have partnered to form private equity investment firm Koa Capital Partners, LLC, and hope to invest in small- to medium-sized businesses serving Hawaii, providing capital but…