Unset IFS before looping over modules.

Out of the box on my machine, IFS was set incorrectly when looping over modules, causing:
```
$ source gvm-init.sh
bash: /Users/ddcapotter/.gvm/src/gvm-broadcast.sh
gvm-common.sh
gvm-current.sh
gvm-default.sh
gvm-flush.sh
gvm-help.sh
gvm-install.sh
gvm-list.sh
gvm-main.sh
gvm-offline.sh
gvm-selfupdate.sh
gvm-uninstall.sh
gvm-use.sh
gvm-version.sh: No such file or directory
```

A simple `unset IFS` will cause the loop to delimitate on newline as expected.

Bash version: 4.3.30(1)-release
MacOSX version: 10.9.5