Remove html tags in i18n translations

[int-y1]

The (newer) reset email looks like this:

<span style="display:block;margin: 0 2px;padding: 1em;border: 3px solid #FFDE05;background-color: #000;border-radius: 6px;font-size: .95em;color: #444;margin-bottom:0.75em">
<div style="display:table;margin-left:2em"><img src="https://avatars1.githubusercontent.com/u/6934864?v=3&s=101" style="display:inline;vertical-align: middle">
<h1 style="font-size:4em;display:inline;vertical-align: middle"><a href="http://localhost:8081" style="text-decoration:none;color:gray"><span style="color: #FFDE05">DM::</span>OJ</a>
      </h1>
</div>
</span>
<div style="display:block;margin: 0 2px;padding: 1em;border: 3px solid #2980B9;background-color: #f8f8f8;border-radius: 6px;font-size: .95em;color: #444;">

<b>Forgot your password on the DMOJ: Modern Online Judge? Don&#39;t worry!</b><br><br>
To reset the password for your account &quot;admin&quot;, click the button below.
<p align="center">
<a href="http://localhost:8081/accounts/password/reset/confirm/MQ-60s-b85dbd13f9d265762557/" style="cursor: pointer;display:block;text-align: center;padding: 4px 2px 5px;color: white;border: 1px solid #666;border-radius: 1px;background: #2980b9;background: linear-gradient(180deg, #00aee0, #2980b9);text-decoration: none;line-height:2em;font-size:1em;width:12em;">Reset Password</a>
</p>
See you soon!
</div>

Side note: The password reset email needs further fixes, but let's not worry about those problems for now.

[codecov-commenter]

Codecov Report

Merging #1921 (3188d5c) into master (592c0d3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1921   +/-   ##
=======================================
  Coverage   46.41%   46.41%           
=======================================
  Files         235      235           
  Lines       13107    13107           
=======================================
  Hits         6084     6084           
  Misses       7023     7023           

Impacted Files	Coverage Δ
dmoj/urls.py	89.47% <0.00%> (ø)
judge/views/submission.py	32.21% <0.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 592c0d3...3188d5c. Read the comment docs.

[Ninjaclasher]

LGTM