Fixes a bug with a unit test failing at certain times of day.

https://travis-ci.org/OpenTreeMap/OTM2/builds/43048572 failed with the
following output:
 File "/home/travis/build/OpenTreeMap/OTM2/opentreemap/treemap/tests/dates.py",
 line 44, in test_mixed_tz_awareness_neq

 d2 = datetime(d1.year, d1.month, d1.day, d1.hour - 1)

 ValueError: hour must be in 0..23

The test took place at around 7:30PM ET, which would put it at 12:30PM UTC.
This caused d1.hour to be 0, which meant d1.hour - 1 was -1, and invalid value.
Merge pull request #1833 from maurizi/fix/test_mixed_tz_awareness_neq

Fixes a bug with a unit test failing at certain times of day.
Fix Explore Map link text

The helper classes 'visible-xs-inline' and 'visible-xs-inline-block'
were added in Bootstrap 3.2
This backports that class temporarily, until we update Bootstrap

Fixes #1840
Merge pull request #1844 from maurizi/fix/1840/explore-map-link

Fix Explore Map link text
Cleanup status.js lint
Anchor popovers inside the managing element

fixes #1838 on github
Add basic species resolver
Add typeahead species resolver
Don't allow empty values on species popover submit
Clean up levenshtein code
Remove reference to changed field name
DRY out import tree species field refs
Validate tree species on other_part
Fix KeyError in non-existent field

In some cases, an validation error in the importer can add error
conditions to a field that may not exist in the row data. These need a
default to avoid key errors.
Merge pull request #1828 from steventlamb/topic/importer_species_resolver_typeahead

Topic/importer species resolver typeahead
Cleanup from previous PR
Create `importer.models` package

Making `species.py` and `trees.py` siblings of `models.py` turns out to have broken South's ability to detect schema migrations in those files.

Initially when splitting up the monolithic `models.py` I had wanted to make a `models` package but ran into migration problems.
Now I've solved those by a migration removing all models (0002) and another adding them back in from the package (0003).
That's OK since nobody has important importer data currently.
Improve importer's file loading

* Add new `LOADING` status for import events
* Show running count as rows are loaded
* Bulk create blocks of row objects (and remove subclass-specific `create_row`)
* Remove `transaction.atomic` on `tasks._create_rows_for_event` and remove rows manually if csv load fails

Also, refactor and simplify file-level validation
* Only `tasks._create_rows_for_event` deals with file-level validation
* Don't read rows if header has errors
* Move "empty file" check from `validate_main_file` to `tasks._create_rows_for_event`
* Rename `validate_main_file` to `validate_field_names`
* Subclasses now override `legal_and_required_fields()` instead of `validate_main_file`

Other refactoring and cleanup
* Add `GenericImportEvent.row_count` property
* Remove unused field `GenericImportEvent.committed`
Fix little bugs