Adds logic to compute dataset bounding box using global attrs
Set max height of table div based on window height

Fixes #125
Transform zero area global attribute bounding boxes to points
Fix box coordinate order for d3 maps
Handle errors when not possible to open DAP endpoint
Handle string casting to float for global bounds

Although the ACDD specifies geospatial_(lat,lon)_(min,max) should be
decimal, (See https://geo-ide.noaa.gov/wiki/index.php?title=NetCDF_Attribute_Convention_for_Dataset_Discovery)
occasionally, there are strings for the geospatial lat/lon
min/max.  Handle these and attempt to cast to string if needing to
compute a bounding box from global attributes.
Display info popup even if dataset has no pings

If a dataset has no ping info, its information popup should now still be
displayed when selected
Allow ERDDAP instances to be indexed

Temporary workaround using regular expression search of the URL to
detect ERDDAP instances.  Fixes #35.
Merge pull request #141 from benjwadams/asset_map_display_info_without_pings

Display info popup even if dataset has no pings
Merge pull request #140 from benjwadams/handle_paegan_dap_open_errors

Handle errors when not possible to open DAP endpoint
Merge pull request #134 from benjwadams/fix_table_scroll

Set max height of table div based on window height
Merge pull request #128 from ioos/boundingbox

Adds logic to compute dataset bounding box using global attrs
Merge pull request #142 from benjwadams/index_erddap_services

Allow ERDDAP instances to be indexed
Fixed select error when marker icon layer not present

If a point indicator icon layer does not exist or is not present, do not
attempt to remove it from the map.  This fixes some select problems when
polygon or linestring areas were selected instead of points.
Adds a arrow to requirements

Arrow is a dependency of another required module. Adding it to the
requirements.txt file will make creating a development environment
smoother.
Merge pull request #143 from benjwadams/fix_asset_map_select

Fixed select error when marker icon layer not present
Merge pull request #144 from ioos/reqs

Adds a arrow to requirements