install-deps: add a yum_install function
install-deps: add a yum_install function

Rather than calling yum each time, check first using rpm if the package
is already installed.

gunesacar/tor-browser-bundle-testsuite,boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite,boklm/tbb-testsuite,boklm/tbb-testsuite,gunesacar/tor-browser-bundle-testsuite