force the encoding of new SafeBuffers to utf-8
force the encoding of new SafeBuffers to utf-8

See the code comment for rationale

test plan: Without this patch applied, you will get encoding errors on
some pages in ruby 1.9.3. With this patch you should no longer get those
errors.

Change-Id: I52fff9c3087ec319cd336e675077e25869abeed3
Reviewed-on: https://gerrit.instructure.com/15467
Reviewed-by: Stanley Stuart <d3942c3cf0aa13de8a95b690bdc33eab29ac4e73@instructure.com>
Tested-by: Stanley Stuart <d3942c3cf0aa13de8a95b690bdc33eab29ac4e73@instructure.com>

leftplusrightllc/canvas-lms,loganrun/pincan,parbros/red-innovadores-lms,fronteerio/canvas-lms,roxolan/canvas-lms,landonwilkins/canvas-lms,HotChalk/canvas-lms,leftplusrightllc/canvas-lms,grahamb/canvas-lms,wimemx/Canvas,wrdsb/canvas-lms,fronteerio/canvas-lms,usmschuck/canvas,venturehive/canvas-lms,wimemx/Canvas,ShreniiNepal/shrenii_lmp,ShreniiNepal/shrenii_lmp,va7map/canvas-lms,efrj/canvas-lms,merichar/canvas-lms,Jyaasa/canvas-lms,utkarshx/canvas-lms,arrivu/arrivu-lms,arrivu/qibla-ecampus,grahamb/canvas-lms,antoniuslin/canvas-lms,skmezanul/canvas-lms,arrivu/hoodemo,arrivu/hoodemo,arrivu/qibla-ecampus,Rvor/canvas-lms,greyhwndz/canvas-lms,utkarshx/canvas-lms,venturehive/canvas-lms,Unow/canvas-lms,leftplusrightllc/canvas-lms,va7map/canvas-lms,wimemx/Canvas,jay3126/canvas-lms,merichar/canvas-lms,kyroskoh/canvas-lms,parbros/red-innovadores-lms,wrdsb/canvas-lms,whalejasmine/canvas-lms,sdeleon28/canvas-lms,arrivu/hoodemo,kyroskoh/canvas-lms,arrivu/arrivu-lms,efrj/canvas-lms,djbender/canvas-lms,sdeleon28/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,nditech/red-innovadores-lms,wye0220/shindig-canvas,SwinburneOnline/canvas-lms,shidao-fm/canvas-lms,sdeleon28/canvas-lms,samuels410/greatlakes-lms,Unow/canvas-lms,landonwilkins/canvas-lms,greyhwndz/canvas-lms,redconfetti/canvas-lms,samuels410/greatlakes-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,skmezanul/canvas-lms,jay3126/canvas-lms,nditech/red-innovadores-lms,va7map/canvas-lms,fronteerio/canvas-lms,whalejasmine/canvas-lms,arrivu/arrivu-lms,jay3126/canvas-lms,skmezanul/canvas-lms,efrj/canvas-lms,sli7246/canvas_branch,rup/Tarrax,sfu/canvas-lms,sfu/canvas-lms,kyroskoh/canvas-lms,skmezanul/canvas-lms,jay3126/canvas-lms,leftplusrightllc/canvas-lms,arrivu/qibla-ecampus,roxolan/canvas-lms,samuels410/greatlakes-lms,utkarshx/canvas-lms,venturehive/canvas-lms,arrivu/jigsaw-lms,Unow/ins,HotChalk/canvas-lms,sfu/canvas-lms,antoniuslin/canvas-lms,Unow/ins,landonwilkins/canvas-lms,nditech/red-innovadores-lms,greyhwndz/canvas-lms,shidao-fm/canvas-lms,wrdsb/canvas-lms,antoniuslin/canvas-lms,roxolan/canvas-lms,nditech/red-innovadores-lms,grahamb/canvas-lms,arrivu/jigsaw-lms,redconfetti/canvas-lms,merichar/canvas-lms,tgroshon/canvas-lms,shidao-fm/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,rup/Tarrax,Rvor/canvas-lms,HotChalk/canvas-lms,juoni/canvas-lms,tgroshon/canvas-lms,greyhwndz/canvas-lms,SwinburneOnline/canvas-lms,parbros/red-innovadores-lms,fronteerio/canvas-lms,sfu/canvas-lms,usmschuck/canvas,sfu/canvas-lms,shidao-fm/canvas-lms,whalejasmine/canvas-lms,Unow/canvas-lms,juoni/canvas-lms,antoniuslin/canvas-lms,roxolan/canvas-lms,Jyaasa/canvas-lms,sdeleon28/canvas-lms,ShreniiNepal/shrenii_lmp,tgroshon/canvas-lms,sli7246/canvas_branch,whalejasmine/canvas-lms,redconfetti/canvas-lms,loganrun/pincan,grahamb/canvas-lms,wye0220/shindig-canvas,landonwilkins/canvas-lms,Rvor/canvas-lms,ShreniiNepal/shrenii_lmp,wye0220/shindig-canvas,sli7246/canvas_branch,venturehive/canvas-lms,kyroskoh/canvas-lms,samuels410/greatlakes-lms,utkarshx/canvas-lms,redconfetti/canvas-lms,Unow/ins,SwinburneOnline/canvas-lms,efrj/canvas-lms,va7map/canvas-lms,juoni/canvas-lms,rup/Tarrax,wrdsb/canvas-lms,loganrun/pincan,usmschuck/canvas,tgroshon/canvas-lms,juoni/canvas-lms,usmschuck/canvas,Jyaasa/canvas-lms,Jyaasa/canvas-lms,Rvor/canvas-lms,HotChalk/canvas-lms,arrivu/jigsaw-lms