Implemented washing of return from ExchangeClient.

You can now define patterns that will be removed from error messages
ExchangeClient returns.

It is imperative to do this, since servers reboot once in a while.

CRB-440: -rens-av-retur-fra-powershell
EventHandler survives springboard reboot now.

CRB-442: -handtering-av-serverunavailableexception
Fixed subject and dest. ids in EmailForward.

Added docstrings too.

CRB-454: -feil-attr-til-changelog-for-emailforward
Including indirect members in count and setting both limits at 16.
Add: Default guestconfig module, `default_guestconfig'
CRB-461-default-guestconfig
Merge pull request #108 in CRB/cerebrum from CRB-454-feil-attr-til-changelog-for-emailforward to master

* commit 'df2ba056689bc08ca39a3b064230de286223a835':
  Fixed subject and dest. ids in EmailForward.
Merge pull request #100 in CRB/cerebrum from CRB-440-rens-av-retur-fra-powershell to master

* commit '2aef408e00957b4100eb2ad64beed98bc8ffcf9d':
  Implemented washing of return from ExchangeClient.
Fixed reporting of ModerationEnabled.

Now, ModerationEnabled should be reported as False, instead of None.

CRB-316: -tilstandsverifisering-av-exchange
Merge pull request #111 in CRB/cerebrum from CRB-461-default-guestconfig to master

* commit 'c17b282dd188d3449071e9687ec36095fccfb177':
  Add: Default guestconfig module, `default_guestconfig' CRB-461-default-guestconfig
Merge pull request #109 in CRB/cerebrum from CRB-179-feil-ved-sjekk-av-antall-nis-grupper to master

* commit '260714c1dbd7193d38ce68db2abacb33679cfcaa':
  Including indirect members in count and setting both limits at 16.
Ignore Exchange DBs if set to zero in cereconf.

This is to be able to define some DBs but without having to choose them
automatically. cereconf should be updated.

CRB-414
Merge pull request #112 in CRB/cerebrum from CRB-316-tilstandsverifisering-av-exchange to master

* commit '9be550e5e215da9c701d1b8bff6d0fc4c4c73670':
  Fixed reporting of ModerationEnabled.
Merge pull request #101 in CRB/cerebrum from CRB-442-handtering-av-serverunavailableexception to master

* commit '51292890922376badcceaf0672c194f64513c9e7':
  EventHandler survives springboard reboot now.
Merge pull request #115 in CRB/cerebrum from CRB-414-vekting to master

* commit '7e10ab06425b1b6ab96d404597b29502d9afb465':
  Ignore Exchange DBs if set to zero in cereconf.
Change recstatus=2 to recstatus=1 all over the generated XML.
Merge pull request #119 in CRB/cerebrum from CRB-469-uia-endre-recstatus-2-til-recstatus-1 to master

* commit '80cd0d5f6144dfd2ccc571e74b200b2511c8b359':
  Change recstatus=2 to recstatus=1 all over the generated XML.