Profiles : Form Display Label s/b empty if Field Label is NULL (uf_field.label)

Users need to be able to include fields on Profile forms w/o them having a label. The original spec for uf_field.label implementation stated that no label s/b rendered on profile forms/selector column headers if the uf_field.label value was NULL. However, the code is currently defaulting to the uf_field.field_name for these cases.

1. Change code to not display label if label col is NULL

2. Modify civicrm_sample.tpl and generate a new copy of civicrm_generated.mysql with uf_field.label values included (these are currently not being set for the sample uf_field records - and we should let the label col value so when we fix item 1. we don't wind up w/ empty labels for all sample form fields).

3. Modify version upgrade sql scripts (sql/civicrm_upgradedb_v1.3_v1.4_41.mysql and sql/civicrm_upgradedb_v1.3_v1.4_40.mysql) to:
3.1 Set civicrm_uf_field.label values for each existing uf_field record based on field_name (or field_name+location_type_id lookup).
3.2 Set civicrm_uf_field.is_searchable =1 where in_selector = 1 and visibility = 'Public User Pages and Listings'
3.3 Set field_type = 'Individual'