added .cov files to gitignore.
adds airspace data, openair format parser.

this commits adds airspace support, with appropriate objects defined in
the common package - new structs Airspace and AirspaceSegment.

it also adds support for the OpenAir format, as defined at:
http://www.winpilot.com/UsersGuide/UserAirspace.asp

this is the first plugin implementation for airspace data.

Fixes #24.
Merge pull request #24 from rochaporto/new/openair#20

parser for openair format (airspace information)
added soaringweb package and basic calls.

Implements #19.
added list and list tests to soaringweb.
added support for single entry soaringweb parsing.
replaced regex with html based parsing.

adds parsing of soaringweb release pages using net/html. adds support
for parsing of multiple releases in a single soaring web pages. adds
support for multiple date formats in the soaring web pages.
dropped err check in html.Parse.

not needed as html.Parse does a really good job at parsing broken html
docs.
Merge branch 'new/soaringweb#19' of github.com:rochaporto/ezgliding into new/soaringweb#19

Conflicts:
	soaringweb/soaringweb.go
	soaringweb/soaringweb_test.go