/account/activate: strip trailing spaces in login field

[php-coder]

When user activates account, specifies login that contains trailing spaces, for example, test and tries to register, he gets an error Login must consist only latin letters, digits, dot, hyphen or underscore.

We should remove trailing spaces before validation and transform this value into test string (that is valid).

What should be done:

• use StringTrimmerEditor for removing spaces (like we're already doing for the name field)
• add integration test for this case (we can use the similar test for the name field as example)