30/UI tag selection

[decentgarlic]

• When creating a new post, the user can select 0 or more of their targeting tags to tag their post with
• Dropdown with tag pop ups and ability to delete tag
• On form post, it'll create a new tag decl for each tag that has been selected - the tag that has been selected becomes the anchoring tag, with the new post (node) being the target tag.

Notes:

• The way I could get the UI tagging to work is to have a hidden field for each tag - I'm unsure if this is the best practise to do it so open to suggestions on how it could be better written
• Issue 29 is also in this PR with the default blog tag that is created for each user
• Currently on post creation, it will create a new tag decl w the tag string being "include_" - this is an assumption that will need to change I think. What if the user wants a "related to" link, instead of a "include" link?