Fix notices and warnings in Export and save mapping

I'm getting quite a few different notices when I use "Select fields for export" (Contacts) and save mappings. Some of them are related to handling "related contacts" - seems like we are trying to save values for phoneTypeId for example when we never actually expose a phone type drop-down.

Also, the code in lines 1132-1136 also seems to have a bug since it doesn't handle 'Primary' location type properly (which is not numeric, but the array key exists).

Example of lots of notices after exporting / saving a mapping which includes related contact->Employee of->email primary:

1. Notice: Undefined variable: imProvider in CRM_Core_BAO_Mapping::buildMappingForm() (line 715 of /Users/dgg/svn/crm_v4.1/CRM/Core/BAO/Mapping.php).
2. Notice: Undefined offset: 1 in CRM_Core_BAO_Mapping::buildMappingForm() (line 661 of /Users/dgg/svn/crm_v4.1/CRM/Core/BAO/Mapping.php).

1. Notice: Undefined variable: phoneType in CRM_Core_BAO_Mapping::buildMappingForm() (line 715 of /Users/dgg/svn/crm_v4.1/CRM/Core/BAO/Mapping.php).
2. Notice: Undefined variable: imProvider in CRM_Core_BAO_Mapping::buildMappingForm() (line 715 of /Users/dgg/svn/crm_v4.1/CRM/Core/BAO/Mapping.php).`
3. Notice: Undefined index: 16 in CRM_Export_BAO_Export::exportComponents() (line 746 of /Users/dgg/svn/crm_v4.1/CRM/Export/BAO/Export.php).