Fix checking unrelated directories by xcodecapp

without this there's no way to convert xib to cib files of archipel because I get `Listing /.DocumentRevisions-V100 failed: Permission denied` from xcodecapp ( checkout the console log here: https://gist.github.com/everplays/5993992#file-xcodecapp-console-log ). I checked it with @aparajita and he said checkout if you've any symbolic links that might cause this issue but there wasn't any. anyways, it's not xcodecapp's problem at all. it's nib2cib that can't find resources ( check its output: https://gist.github.com/everplays/5993992#file-nib2cib-output-without-patch ) and somehow causes that xcc's odd behavior.

with this patch, output of nib2cib is like ( https://gist.github.com/everplays/5993992#file-nib2cib-output-with-patch ) and xcc converts archipel's MainMenu.xib file without any problem ( https://github.com/ArchipelProject/Archipel/blob/master/ArchipelClient/Resources/en.lproj/MainMenu.xib ).

I also attached a screenshot from xcodecapp's error:

![screen shot 2013-07-14 at 1 53 01 pm](https://f.cloud.github.com/assets/194719/794164/ee5e00b8-ec79-11e2-94f3-01373c61dd93.png)