Set proper "content-type" while calling JwtService.Reset()

[iRay]

During "LogOut", JwtService.Reset() doesn't set "content-type" header that leads to "XML Parsing Error: no root element found" in FireFox.
This PR simply adds proper header.

[paskal]

@iRay, please copy the exact change to the v2 directory, as it will be released soon and will need those changes.

[iRay]

@paskal ok, got you, thx.

[coveralls]

Pull Request Test Coverage Report for Build 9549266452

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 82.758%

---

Totals
Change from base Build 8627959567:	0.01%
Covered Lines:	2563
Relevant Lines:	3097

---

💛 - Coveralls

[paskal]

@iRay apologies for not being clear on that: could you please add the change both to v1 and v2?

[coveralls]

Pull Request Test Coverage Report for Build 9563737651

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 82.758%

---

Totals
Change from base Build 8627959567:	0.01%
Covered Lines:	2563
Relevant Lines:	3097

---

💛 - Coveralls

[iRay]

@paskal you was clear enough and I added the same changes to v2. Maybe I missed something else?

[coveralls]

Pull Request Test Coverage Report for Build 9563737652

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 82.758%

---

Totals
Change from base Build 8627959567:	0.01%
Covered Lines:	2563
Relevant Lines:	3097

---

💛 - Coveralls

[iRay]

@paskal you was clear enough and I added the same changes to v2. Maybe I missed something else?

Or maybe you meant I need to create another branch and new PR with changes for v1 and v2?

[umputun]

LGTM, thx

[paskal]

Now it's good, thank you!

[paskal]

This commit caused issue umputun/remark42#1812. I think changing the context type to text/plain would fix the situation as we don't respond with any text and it's not a valid json.