Description of problem:

Here is the problem, 
* we currently have a unique constraint on rhnReleaseChannelMap for product, version, channel_arch_id, is_default. So if we have more than 2 eus channels for the same RHEL it will fail as is_default is the only unique value. 

*Now sync  rhel-x86_64-server-5.3.z, rhel-x86_64-server-5.2.z and rhel-x86_64-server-5.1.z, product-version-channel_arch_id are same for all three channels, but is_default is 'Y' for one(newest) and 'N' for the other two causing the unique constraint. 

* Now we need another unique column, So to support all available eus channels for the same RHEL on satellite, rhnreleasechannelmap should perhaps include 'release' as well in the unique constraint which would be 5.2.0.2 or 5.3.0.3 etc. This way we can drop is_default from db and include release instead and let your patch decide the is_default. 

Version-Release number of selected component (if applicable):

How reproducible:
always

Steps to Reproduce:
1. satellite-sync -c rhel-x86_64-server-5.3.z -c rhel-x86_64-server-5.2.z -c rhel-x86_64-server-5.1.z
11:48:49 Red Hat Network Satellite - live synchronization
11:48:49    url: https://satellite.rhn.webqa.redhat.com
11:48:49    debug/output level: 5
11:48:49    +++ Satellite synchronization tool checking in.
11:48:49    +++ Entitled satellite validated.
11:48:49    db:  rhnsat/<password>@rhnsat
...

(Check logs/email for potentially more detail)

<rhnFault class (code = 54, text = 'ORA-00001: unique constraint (RHNSAT.RHN_RCM_PVA_DEF_UNIQ) violated
')>
(54, 'ORA-00001: unique constraint (RHNSAT.RHN_RCM_PVA_DEF_UNIQ) violated\n', '\n     Package Upload Failed due to uniqueness constraint violation.\n     Make sure the package does not have any duplicate dependencies or\n     does not already exists on the server\n     ')
  
Basically what needs to happen is:

We need to support the hosted ported changes from bug#356951(which are currently in master not vader).

1. DB Changes:
 - Drop is_default column
 - Drop unique constraint on product,version,channel_arch_id,is_default
 - Add unique constraint on product,version,channel_arch_id,release instead

2. Backend Changes:
 - Fix satellite-sync and exporter to exclude the is_default from the import and export queries and take into account the release.