Adds logic to compute dataset bounding box using global attrs
Properly formed HTML for script and link tags
Fixed unclosed <a> tag
Merge pull request #130 from benjwadams/fix_html_validation_errors

Fix HTML validation errors
Set max height of table div based on window height

Fixes #125
Switched to Leaflet for map vector feature display

Now utilizing leaflet for vector overlays instead of d3.  Also adds
mouseover/mouse click events on map.

Also coincidentally addresses and fixes #127 point 1).

Since the vector display has been switched to Leaflet, this will now
allow #101 to be addressed.
More efficient mechanism for adding features
Working marker cluster with menu selection
Re-enabled MultiPoint features

Mainly for presentational purposes.  Please note #133.
Merge pull request #135 from benjwadams/cluster_markers

Cluster point features
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