Thank you for the logs. The log doesn't show anything weird in particular, just an abrupt abort at the moment it extracts gmscore, which is the largest compressed folder.
This supports my theory that it might be problem that we run out of RAM.
I have made a special build that extracts some intermediate steps to /sdcard/ instead of to /tmp/, I would like you to try it:
https://www.dropbox.com/s/cq8l1gojcc9vgzo/open_gapps-arm-5.1-stock-20150711-experiment.zip?dl=0
Make sure you have at least some space available at /sdcard/ (300MiB should be sufficient), and some empty folders as left-overs after installation will be at /sdcard/Open-GApps/ after installation, which can safely be removed.
Could you please report back whether that builds works for you, and collect again the logs?