inputs/import.stats.xls: updated import times

/README.TXT: Full database import: time to wait for the import to finish: updated to time in inputs/import.stats.xls

bugfix: bin/import_all: `rm inputs/.TNRS/tnrs/tnrs.make.lock`: need to use `"rm"` instead of `rm` so that we don't use any rm alias the user might have in their shell (import_all is run in the calling shell so that the jobs are owned by the calling shell)

bugfix: mappings/VegCore-VegBIEN.csv: don't map datasetURL to source.url for taxa-only data (this mapping should only occur for Source tables)

bin/import_all: added step to remove any leftover TNRS lockfile (previously done manually)

planning/timeline/timeline.2013.xls: updated for progress

bugfix: lib/sql_io.py: put_table(): Getting output table pkeys of existing/inserted rows: need to include the index cond in the join condition here, too (using var join_custom_cond), so that an index scan can be used instead of a much slower full-table sort

bugfix: schemas/vegbien.sql: locationevent: locationevent_unique_within_location unique index: added COALESCE expression around location_id since it is nullable, and this is needed for the left and right sides of the join to exactly match up to use an index scan

bugfix: lib/sql_io.py: put_table(): DuplicateKeyException: need to include any index cond in the join condition, so that an index scan can be used instead of a much slower full-table sort (otherwise the query planner will not know that it can restrict results to rows satisfying the index cond)

lib/sql_gen.py: Join: added custom_cond param that can be used to add to the JOIN condition