873313 - Very high memory usage during repo sync

Squashed commit of the following:

commit 7de2d3a1f84e9829a5461fe0bd2d0dd8af5e0ee0
Author: John Matthews <jwmatthews@gmail.com>
Date:   Thu Mar 21 18:06:02 2013 -0400

    Unit tests for YumPackageDetails and ensuring SaveThread is calling sync_conduit.save_unit()

commit 24a5c07685fca6168afc1399edd416c5d3c3f605
Author: John Matthews <jwmatthews@gmail.com>
Date:   Thu Mar 21 15:00:36 2013 -0400

    Exclude tree files from warning message in SaveThread

commit c7d61aa3c4fe8a0732be2f75ddda2795c4e04037
Merge: 89e6c40 d043a42
Author: John Matthews <jwmatthews@gmail.com>
Date:   Thu Mar 21 13:42:44 2013 -0400

    Merge remote branch 'upstream/pulp-2.1' into jmatthews_sync_perf

commit 89e6c408420ef0b63439bb25bba56d0759f780a9
Merge: b4270a4 209b9ab
Author: John Matthews <jwmatthews@gmail.com>
Date:   Thu Mar 21 12:08:35 2013 -0400

    Merge remote branch 'upstream/pulp-2.1' into jmatthews_sync_perf

commit b4270a4e06e5f27f5c9ff74daaad1ee5bac6e415
Author: John Matthews <jwmatthews@gmail.com>
Date:   Wed Mar 20 18:42:56 2013 -0400

    Fix for saving distributions and drpm units

commit d2bc9b8896114278c52d8631d4d78cf719314013
Merge: 83c5663 0b058b7
Author: John Matthews <jwmatthews@gmail.com>
Date:   Wed Mar 20 14:47:05 2013 -0400

    Merge remote branch 'upstream/pulp-2.1' into jmatthews_sync_perf

    Conflicts:
    	pulp_rpm/plugins/importers/yum_importer/importer_rpm.py

commit 83c5663625ca9975985b42bd07b8feadafa86c07
Author: John Matthews <jwmatthews@gmail.com>
Date:   Wed Mar 20 14:11:43 2013 -0400

    Updated SyncReport for errors to not contain tuples as keys

commit 125d497ef789cc045d5414c159694731fb9a290b
Author: John Matthews <jwmatthews@gmail.com>
Date:   Wed Mar 20 09:04:12 2013 -0400

    Added repo_label to logging output from SaveThread

commit 4e31f0e51ba5cfbadf0fbfdd3e9ea8f1a697d85e
Merge: aeb55ad 7135f1a
Author: John Matthews <jwmatthews@gmail.com>
Date:   Tue Mar 19 11:24:51 2013 -0400

    Merge remote branch 'upstream/pulp-2.1' into jmatthews_sync_perf

commit aeb55ad2b4b32a96a7ad8d5553bac8c6f49eeb4e
Author: John Matthews <jwmatthews@gmail.com>
Date:   Mon Mar 18 18:24:22 2013 -0400

    Fix for cancel_sync

commit 007f5a50b18c5ad5031aa0190fc0ed8b2dc9e851
Author: John Matthews <jwmatthews@gmail.com>
Date:   Mon Mar 18 10:23:19 2013 -0400

    Introduced YumPackageDetails class for looking up yum metadata xml snippets from a filepath

commit cd47838bf5a65101e54468de5e280813011adcee
Author: John Matthews <jwmatthews@gmail.com>
Date:   Mon Mar 18 10:20:09 2013 -0400

    Introduced SaveThread to save units in parallel to downloading, restructured how we form summary report
Merge pull request #159 from jwmatthews/jmatthews_bz873313

873313 - Very high memory usage during repo sync