[arcanist] properly handle arguments with spaces
[arcanist] properly handle arguments with spaces

Summary:
The new wrapper shell script that is bin/arc does not correctly
handle arguments with spaces in them.

Test Plan:
added a print_r($argv) to scripts/arcanist.php and ran bin/arc -m
"testing something" to see that "testing something" got passed in as
one argument instead of two.

Reviewers: jungejason, epriestley

Reviewed By: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2066

aik099/arcanist,alexmv/arcanist,phacility/arcanist,wikimedia/phabricator-arcanist,memsql/arcanist,KieranHayes/arcanist,julkiewicz/arcanist,calblueprint/arcanist,julkiewicz/arcanist,haskell-infra/arcanist,fivestars/arcanist,eSpark/arcanist,folsom-labs/arcanist,sneakpeeq/arcanist,phacility/arcanist,fivestars/arcanist,Khan/arcanist,aik099/arcanist,dguo-coursera/arcanist,kevinseelbach/arcanist,coursera/arcanist,calblueprint/arcanist,wxstars/arcanist,uber/arcanist,codelabs-ch/arcanist,alexmv/arcanist,Symplicity/arcanist,chundongwang/arcanist,sneakpeeq/arcanist,zhihu/arcanist,PageUpPeopleOrg/arcanist-patches,phacility/arcanist,haskell-infra/arcanist,Symplicity/arcanist,wharris/arcanist,calblueprint/arcanist,wharris/arcanist,kevinseelbach/arcanist,dguo-coursera/arcanist,haskell-infra/arcanist,hach-que/arcanist,chundongwang/arcanist,memsql/arcanist,julkiewicz/arcanist,r4nt/arcanist,wharris/arcanist,wikimedia/phabricator-arcanist,Symplicity/arcanist,hach-que/arcanist,codelabs-ch/arcanist,zhihu/arcanist,dguo-coursera/arcanist,PageUpPeopleOrg/arcanist-patches,coursera/arcanist,PageUpPeopleOrg/arcanist-patches,Khan/arcanist,eSpark/arcanist,r4nt/arcanist,coursera/arcanist,fivestars/arcanist,folsom-labs/arcanist,Khan/arcanist,aik099/arcanist,sneakpeeq/arcanist,kevinseelbach/arcanist,phacility/arcanist,wxstars/arcanist,jra3/arcanist,chundongwang/arcanist,memsql/arcanist,Khan/arcanist,zhihu/arcanist,haskell-infra/arcanist,codelabs-ch/arcanist,wharris/arcanist,hach-que/arcanist,eSpark/arcanist,uber/arcanist,wxstars/arcanist,uber/arcanist,julkiewicz/arcanist,alexmv/arcanist,memsql/arcanist,folsom-labs/arcanist,r4nt/arcanist,Symplicity/arcanist,fivestars/arcanist,KieranHayes/arcanist,calblueprint/arcanist,r4nt/arcanist,folsom-labs/arcanist,eSpark/arcanist,KieranHayes/arcanist,sneakpeeq/arcanist,wxstars/arcanist,hach-que/arcanist,uber/arcanist,aik099/arcanist,kevinseelbach/arcanist,phacility/arcanist,chundongwang/arcanist,wikimedia/phabricator-arcanist,jra3/arcanist,PageUpPeopleOrg/arcanist-patches,alexmv/arcanist,dguo-coursera/arcanist,coursera/arcanist,jra3/arcanist,KieranHayes/arcanist,codelabs-ch/arcanist,wikimedia/phabricator-arcanist,codelabs-ch/arcanist,zhihu/arcanist,jra3/arcanist