fix recently revealed errors on Solr XML views

A recent change allowed/caused objects to have changes that did not
previously.  This revealed that the Solr XML views have had
long-standing __errors__ on them (but were previous inconsequential).

If my memory server correctly these fields are part of the interface of
Genome::Solr::View::Xml (and should be defined on that base class) but
for now I am just setting fields optional that leave a Solr XML view in
an erroneous state after calling content();

Added tests for and corrected the following views:

Genome::Config::AnalysisProject::View::Solr::Xml
Genome::Individual::View::Solr::Xml
Genome::InstrumentData::Imported::View::Solr::Xml
Genome::InstrumentData::Solexa::View::Solr::Xml
Genome::Library::View::Solr::Xml
Genome::Model::Build::View::Solr::Xml
Genome::Model::View::Solr::Xml
Genome::ModelGroup::View::Solr::Xml
Genome::ProcessingProfile::View::Solr::Xml
Genome::Project::View::Solr::Xml
Genome::Sample::View::Solr::Xml
Genome::Sys::User::View::Solr::Xml
Genome::Taxon::View::Solr::Xml

Have not corrected the following views due to believed irrelevance:

Genome::InstrumentData::FlowCell::View::Solr::Xml
Genome::PopulationGroup::View::Solr::Xml
Genome::Site::TGI::Project::View::Solr::Xml
Genome::Sys::Email::View::Solr::Xml
Genome::Sys::Service::Set::View::Solr::Xml
Genome::Wiki::Document::View::Solr::Xml
Genome::WorkOrder::View::Solr::Xml