added ability to specify not required parameter for action link. Fixe…

[wolendranh]

action_link changes and fixes.

Description

Fixed action link title attribute that was broken.
Added ability to specify additional custom attributes for action link.
Updated documentation.

Example case:
Add attribute

target="_blank"

to open link in new tab.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

[coveralls]

Coverage decreased (-0.007%) to 73.543% when pulling ec3298d on feature/add_custom_action_link_attributes into c6b482a on develop.

[coveralls]

Coverage decreased (-0.02%) to 73.531% when pulling 8c386d4 on feature/add_custom_action_link_attributes into c6b482a on develop.

[mmarcos]

I think it's fine to support attributes, but it's better to have them inside the third parameter instead of adding a fourth positional parameter which makes things a bit complex, the same idea is already used for formaction, which is sent in the third parameter inside the dictionary and recognised as a special keyword.

So you could do:
(label, url, {"attributes": {attr1: val1, attr2: val2}, ...})