Missing html import in Eso.query_survey()
Fixed failing Eso remote tests
Replaced commons.radius_to_unit by Angle()
Replaced deprecated UnitsException by UnitsError
Updated error message in irsa_dust test.
Fixed urlopen use.
Removed radius_to_unit tests.
Merge pull request #324 from jwoillez/fixes_for_astropy0.4

Many fixes for astropy0.4 and remote tests
Fixed handling of duplicated form inputs
Do not add forms inputs without name to payload
Updated documentation for Eso package.
Minor sphinx improvement.
Added help option to Eso.instrument_query()
Improved Eso.query_instrument() interface.

Using `columns` and `column_filters` keywords instead of the generic
`**kwargs`.
Improved help for query_instrument()

A checkbox looking like `[ ]` now shows which columns can be
controlled. The default columns in the output are ticked like `[x]`.
Added beautifulsoup4 dependency.
Added beautifulsoup4 to .travis.yml