Icon svg and font baseline fixes

fixes CNVS-17240
fixes CNVS-17214

This fixes some of the alignment issues we've been having on our
svgs and makes it so they align properly.

Test plan:

- Go to styleguide and look at icons - they all should be there :)

UI Dev plan:
- Go to an html file in Canvas (I just used application.html.erb)
- Add the dummy html to the file (this is throw away) and make
sure on refresh that the eye icon and the trash icon align, as well
as the import/export icons for gradebook buttons

Dummy html:

<div style="padding: 30px;">
  <i class="icon-eye"></i>
  <i class="icon-trash"></i>
  <br/>
  <br/>
  <button class="Button">
    <i class="icon-gradebook-import"></i>
    Import Stuff
  </button>
  <button class="Button">
    <i class="icon-gradebook-export"></i>
    Export Stuff
  </button>
</div>

Change-Id: Ia324abf8bb65194f06e65cff0d61f57f630053d3
Reviewed-on: https://gerrit.instructure.com/45278
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Chris Hart <chart@instructure.com>
Product-Review: Chris Hart <chart@instructure.com>
QA-Review: Anna Koalenz <akoalenz@instructure.com>