Encode share course URLs and use the right protocol

Description

This fixes the social buttons to recommend a course (through Twitter and e-mail) to URL-encode the shared URLs and to use `https://` when required.

Without this fix, the tweet contains this text:
```
I just enrolled in Some Scripting Course through @MyName: http://edu.mydomain.com/courses/course-v1:MyUniversity ABCD100 v1/about
```
With the fix, it gets `https://` and `+` and becomes:
```
I just enrolled in Some Scripting Course through @MyName: https://edu.mydomain.com/courses/course-v1:MyUniversity+ABCD100+v1/about
```

Description goes here. e.g. This PR contains the LibraryContent XBlock, which allows to display library content in a course.

*JIRA tickets*: None

*Discussions*: None

*Dependencies*: None

*Screenshots*: None

*Sandbox URL*: None

*Partner information*: None

*Deployment targets*: N/A

*Merge deadline*: None

*Testing instructions*:

1. Go to http://localhost:8000/courses/course-v1:edX+DemoX+Demo_Course/about
2. Locate the Twitter icon, in the right, and click it
3. Notice that the Twitter text box contains a URL in the format `http://your_local_hostname/courses/course-v1:edX+DemoX+Demo_Course/about`, with `+` signs (and not spaces)
4. Optionally, check in another instance (without this fix) that the URL had spaces instead of `+`
5. Deploy an instance which has SSL enabled, with this fix
6. Check that the Twitter message uses `https`, not `http`

*Author notes and concerns*:
None

*Reviewers*

  • [ ] @cgopalan

  • [ ] edX reviewer[s] TBD

*Settings*
None

Done

Assignee

Unassigned

Reporter

Open Source Pull Request Bot

Contributor Name

Daniel Clemente Laboreo

Repo

edx/edx-platform

Customer

Epic Link

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Platform Map Area (Levels 3 & 4)

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Unset