Add HTTP Basic Authentication support for portable libraries

Issues:
- Portable libraries do not support CredentialCache and thus
multiple credentials, which may be necessary in case of
proxies and credentials.

- Portable libraries do not support PreAuthenticate.

- Portable libraries do not support redirect follow-ups.
Redirection has been defined for full profile, and it will affect
all and not just authentication scenarios.

- It's unclear if authentication function properly in Silverlight
using the browser stack or should "WebRequest.RegisterPrefix
("http://", WebRequestCreator.ClientHttp)
WebRequest.RegisterPrefix("https://",
WebRequestCreator.ClientHttp)" added.

In that case also namespaces
System.Windows.Browser and System.Net.Browser should
be opened and appropriate libraries added.

Some of these issues are concerned if one wants to handle authentication
in presence of redirects and how to build the case of OAuth.
New preprocessor directive defined in DefineConstantTargets

The new prerocessor directive, FX_NO_WEBREQUEST_AUTH, is now defined in
src\DefineConstantTargets.targets instead of the individual project
files. This directive also replaces all of the other new ones that were
defined in the individual project files.
Added FsCheck package and JsonValueProperties test file
Merge branch 'master' into add_fscheck_tests_for_json
encode name of json object properly
Add EmbeddedResource parameter to Json and Xml providers

This was triggered by the issue in Twitter: https://github.com/fsprojects/FSharp.Data.Toolbox/issues/1

The problem is that `FSharp.Data.Toolbox.Twitter.dll` exposes the types
generated by the JSON type provider to the caller - so the methods in the
Twitter API return types generated by the type provider from sample JSON
files (I think this is reasonable - if we had to re-write all the type
declarations by hand, then this would be hard work).

The problem is that the samples are in a local folder (`json/foo.json`)
and when you build `FSharp.Data.Toolbox.Twitter.dll`, you do not want to
always keep them around (because referencing the Twitter API will trigger
the type provider and the type provider will be looking for them).
Embedding the samples inline also does not work - they are just too long
and the F# compiler cannot deal with them.

With this change, we can say `JsonProvider<"sample.json", EmbeddedResource="MyLib,sample.json">`.
The type provider will first try to load `MyLib` and find the resource
there (so, when you are referencing compiled `FSharp.Data.Toolbox.Twitter.dll`,
it will find the resource there). If this fails, it falls back to standard
directory search (which handles the case when you are compiling
`FSharp.Data.Toolbox.Twitter.dll` itself).

I'm not entirely happy with this solution (feels a bit hacky), but I do not
think that there is any other way - aside from making the type providers
generative, which would be nice thing to do, but AFAIK not something that'll
happen very soon.
Add documentation for EmbeddedResource parameter
Merge pull request #599 from tpetricek/master

Add EmbeddedResource parameter to Json and Xml providers
Fix wrong error messages being returned when sample files are not found + Add resource support for csv + Don't generate GetSample(s) method for resources + Fix signature tests
Merge pull request #600 from ovatsus/master

Embedded resources support
Temporary workaround for #587
Fix TeamCity build
Fix loading of resources
Release 2.0.7
Prevent locking of files when reading samples from embedded resources
Minor edit to template
Added latest changes for decimal, DateTime, DateTimeOffset generation from codeplex

https://fsharp3sample.codeplex.com/SourceControl/changeset/24784
https://fsharp3sample.codeplex.com/SourceControl/changeset/24770
https://fsharp3sample.codeplex.com/SourceControl/changeset/24765
Merge pull request #602 from 7sharp9/master

Added latest changes for decimal, DateTime, DateTimeOffset generation from codeplex
Fix for #560
Fix failing doc test