Remove email_validator gem and allow apostrophe as a valid character in email.
Sort issues in milestone

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Test for the apostrophe in the email
Merge branch 'milestone-issue-position' into 'master'

Milestone issues sorting

Now issues save sort position inside milestone lists

Part of #1207
Merge branch 'email_with_apostrophe' into 'master'

Email with apostrophe

Fixes #1225