dep ensure reports warnings, lock file has _many_ changes

[james-async]

running dep ensure on HEAD results in the following warning messages:

dep: WARNING: unknown field in manifest: projects
dep: WARNING: unknown field in manifest: solve-meta

I'm using Dep 0.4.1 and Go version 1.10.1. This may or may not be causing the failure to run the tests. But the first thing I did upon cloning is dep ensure, and then go test ./.... And the service_provider_test.go is failing with these differences between actual and expected:

13c13
<         <ds:DigestValue>KsbyS2V2/QCarAksPQyV5s3PVDk=</ds:DigestValue>
---
>         <ds:DigestValue>fGqTakd3fq3s1utz7xTvzJtQc+E=</ds:DigestValue>
16c16
<     <ds:SignatureValue>paj/Jq/TTvYXu35Jtyevmu8bn2DZecfaj/wu8l7mY2sN++w9QL/sLZoyyJk6WsAsS0NMMOt8o5WN7EU+bVlbQ6VQbf2VO9gEPbONMdpQ8gfrvMiLo5vRS22iRaPehIH8gvWxAq64vWWt94OihpndNRt782K/0h/NvXBj+4vK7V8=</ds:SignatureValue>
---
>     <ds:SignatureValue>yXty6VQCvvF6QAR+vXZtLq2/r8Jt2B9jExD1vVfvWY+S1sKPZbNbaKl69YHYXU8lkhymlVNaMsaezQWDisbNfPe0R0UWysp2rfIXpVDGTdp/YHPj1MIODMPrlgWFfcJjgGxox0tTVzaFyOJFSPhn4G8wEI86WHuePnjRcenfxyk=</ds:SignatureValue>
26c26
<   <this-is-an-encrypted-assertion/>
---
>   <this-is-an-encrypted-assertion xmlns="http://www.w3.org/XML/1998/namespace"/>

That last one, with the additional xmlns could be caused by differences in dependency versions. but the earlier 2 differences.... I can't rationalize from skimming the test.

[dherbst]

I think the default namespace won't be added explicitly like this. I tried to add it manually like below, but the encoder does not add the xmlns when it the default as far as I can tell.

req.AssertionEl = etree.NewElement("this-is-an-encrypted-assertion")
req.AssertionEl.CreateAttr(":xmlns", "http://www.w3.org/XML/1998/namespace")

So I removed it in this PR and replaced the digest and signature without it.
#158

[dherbst]

#158 was merged, which fixes the test. #156 was merged to update the dep file.

@james-async Can this issue be closed since the tests now run clean?