Fix installs on DP7

Apple radar 18216493 filed 2014-09-03

This manifests as being unable to install gems with C extensions,
because the linker will fail unable to find the CrashReporterSupport
framework
Fix missing underscore
rbconfig.rb is owned by root, so we need sudo

... also quiet down grep
Merge pull request #65 from boxen/dp7-fix

Fix installs on Yosemite DP7