Fix #141 & Fix #1392: Update topic description

[rt4914]

Explanation

Fixes #141 & #1392

Currently in develop, the topic description in InfoFragment supports rich text and this PR removes that support because topic description will be plain text only.

Note: I have just removed one particular test case in this and if you want to run/check the existing test cases you can run that specifically on Nexus S device because at the time of development of this PR that device was finalised for testing purposes. On other high-end devices these test cases will fail and it can only be fixed once #1379 is finished.

Before

After

Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The PR explanation includes the words "Fixes #bugnum: ..." (or "Fixes part of #bugnum" if the PR only partially fixes an issue).
• The PR follows the style guide.
• The PR does not contain any unnecessary auto-generated code from Android Studio.
• The PR is made from a branch that's not called "develop".
• The PR is made from a branch that is up-to-date with "develop".
• The PR's branch is based on "develop" and not on any other branch.
• The PR is assigned to an appropriate reviewer in both the Assignees and the Reviewers sections.

[veena14cs]

LGTM.

[anandwana001]

@rt4914 What if the text is a bit long like this?
is this good to go or we should have some max length limit and leave some space at the end to look it good?

[anandwana001]

LGTM.
nit changes to prevent ktlint failure.

[rt4914]

@rt4914 What if the text is a bit long like this?
is this good to go or we should have some max length limit and leave some space at the end to look it good?

This is correct, text length has been controlled correctly in app as well as the oppia backend.