Test for #147
Fixes #147
Remove unneeded open
I added a client certificate parameter to AsyncRequestDetailed, AsyncRequest, RequestDetailed and Request
included Ovatsus' comments 

need to add constant FX_NO_WEBREQUEST_CLIENTCERTIFICATES to https://github.com/fsharp/FSharp.Data/blob/master/src/DefineConstants.targets
Merge pull request #148 from ovatsus/JsonBug

Fix JsonProvider bug
Update links in Readme
Merge pull request #155 from tpetricek/master

Update README links
added failwith to if fx_no_webrequest_clientcertificates
added FX_NO_WEBREQUEST_CLIENTCERTIFICATES targetframework groups
changed "cert" to certificate and added a short example to /samples/library/http.fsx
Support for Windows Phone 7.1
Fix crash in Http.Request on wp8 and win8 when download not possible
Improve Http error handling in wp8 and win8
Improve naming of JsonProvider and ApiaryProvider generated types
Merge pull request #152 from remkoboschker/patch-1

I added a client certificate parameter to AsyncRequestDetailed, AsyncReq...
Tweaks in documentation for certificates
Merge pull request #162 from ovatsus/WP71

Support for Windows Phone 7.1
Merge pull request #166 from ovatsus/JsonNames

Improve naming of JsonProvider and ApiaryProvider generated types
Update release notes