InvalidLinkBear: Remove FTP from regex

[refeed]

Remove 'ftp' from regex variable in find_links_in_file()
method because Python requests library can't fetch the FTP
status code.

Closes #906

[gitmate-bot]

Thanks for your contribution!

Reviewing pull requests take really a lot of time and we're all volunteers. Please make sure you go through the following check list and complete them all before pinging someone for a review.

• I have rebased properly. Please see this for a tutorial.
• I have gone through the commit guidelines and I've followed them:
  • I have followed the guidelines for the commit shortlog.
  • I have followed the guidelines for the commit body.
  • I have included the issue URL.
  • I have used the Fixes keyword if the commit fixes a real bug and the Closes keyword if it adds a feature/enhancement. See more here.
• I have run all the tests and they all pass. That includes that all CI (below) is green - if GitMate issues appear you will have to amend your commits, pushing new commits on top is not sufficient!

As you learn things over your Pull Request please help others on the chat and on PRs to get their stuff right as well!

[stefanbalas]

Hey, it appears that appveyor failes due to some bad import that is fixed in another pr. Wait untill that one is merged. Thanks.

[Adrianzatreanu]

aaaand it was fixed, please rebase and everything will pass! :)

[refeed]

@Adrianzatreanu rebased

[Adrianzatreanu]

ack 89e1108

[Adrianzatreanu]

@rultor merge

[rultor]

@rultor merge

@Adrianzatreanu OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge

@Adrianzatreanu Done! FYI, the full log is here (took me 1min)