~ in privateKey does not work

From the tail of my `strace -f -e trace=file grunt`:

`stat("~/.ssh/chrome-apps.pem", 0x7fff25cec6d0) = -1 ENOENT (No such file or directory)`

yet:

`ls ~/.ssh/chrome-apps.pem -l
-rwx------ 1 rektide rektide 1090 2013-03-06 22:20:14 -0500 /home/rektide/.ssh/chrome-apps.pem*`

The ~ in the privateKey option needs to be converted into the users home directory. Opening a file with ~ in it does not work.