generalPurposeHandler, throws exception on not 2xx
Add status message to HttpClientError
Add comment about exception specificity
Merge branch 'gcollins'
Revert non-Linux certificate verification

Restore existing behaviour that the default is certificate validation
against /etc/ssl/certs. Open task to non-free operating systems to
find an appropriate default configuration if that is possible

Consolidate documentation of withOpenSSL requirement.
Rename generalPurposeHandler to concatHandler'
Rebuild tags if building documentation
Expose establishConnection function
Add formal test to ensure Host: header

Also, this restores the orignal test of the logic in Connection that
checks to ensure that the [virtual] host name is cached and passed
through to the Host: field.
Add text dep to the testsuite.