Update layout-attrs.md
docs-468: Doc computed block & inline function support.
Fixes #468 & #427.
Also updates .gitignore, which was ignoring some of our samples.
Add link to known issue.
Address comments:

- Change default value to number.
- Add whitespace in expression.
Merge pull request #567 from lucasloisp/patch-1

Add 'flex' attribute to element in the 'layout attributes' page
Merge pull request #569 from arthurevans/computed

docs-468: Doc computed block & inline function support.
Update min files
Merge branch 'master' of https://github.com/Polymer/docs
Adds global filters docs for #571
added heads-up for Polymer/polymer#677 

as there was (pedanticly spoken) a noscript attribute missing, I did add the script tag to hint to the workaround to Polymer/polymer#677
Updated Core Icons article for styling changes:

  fill => color
  size => width,height

Also added examples for styling icons inside other components,
edited for style, and made headings more consistent.
Updated to address comments.
Merge pull request #575 from arthurevans/icon-style

Updated Core Icons article for styling changes:
Make sure docs build under jekyll 2.2. Just use raw commands
Merge branch 'master' of https://github.com/Polymer/docs
Global filters: address feedback
hifi favicon
Merge pull request #573 from Polymer/globalfilters

Adds global filters docs for #571
Use hidden attribute instead of show class.
display:block breaks elements that use display:flex box
Clarify the need to update `bower.json`

If the names in `bower.json` are not updated to the new element, the `gp.sh` script will build broken links still pointing to `seed-element`.

Perhaps this will save others from some confusion.