constant('SID')

ISSUE-82 - (continuation of) Fix odd PHP quirk which triggers fatal error "Allowed memory size of --- bytes exhausted" when accessing SID constant.

(adding to zc_install for consistency)
<a href='#crh-start'></a><a href='#crh-data-%7B%22processed%22%3A%20%5B%22https%3A//github.com/zencart/zc-v1-series/pull/159%23issuecomment-55624689%22%2C%20%22https%3A//github.com/zencart/zc-v1-series/pull/159%23issuecomment-55633620%22%2C%20%22https%3A//github.com/zencart/zc-v1-series/pull/159%23issuecomment-55656159%22%5D%2C%20%22comments%22%3A%20%7B%22General%20Comment%22%3A%20%7B%22html_url%22%3A%20%22https%3A//github.com/zencart/zc-v1-series/pull/159%23issuecomment-55624689%22%2C%20%22comments%22%3A%20%5B%7B%22body%22%3A%20%22%3A%2B1%3A%22%2C%20%22created_at%22%3A%20%222014-09-15T17%3A18%3A40Z%22%2C%20%22user%22%3A%20%7B%22avatar_url%22%3A%20%22https%3A//avatars.githubusercontent.com/u/2963958%3Fv%3D2%22%2C%20%22html_url%22%3A%20%22https%3A//github.com/lhungil%22%7D%7D%2C%20%7B%22body%22%3A%20%22%3A%2B1%3A%20%22%2C%20%22created_at%22%3A%20%222014-09-15T18%3A18%3A20Z%22%2C%20%22user%22%3A%20%7B%22avatar_url%22%3A%20%22https%3A//avatars.githubusercontent.com/u/227354%3Fv%3D2%22%2C%20%22html_url%22%3A%20%22https%3A//github.com/zcwilt%22%7D%7D%2C%20%7B%22body%22%3A%20%22%3Ashipit%3A%22%2C%20%22created_at%22%3A%20%222014-09-15T20%3A48%3A03Z%22%2C%20%22user%22%3A%20%7B%22avatar_url%22%3A%20%22https%3A//avatars.githubusercontent.com/u/227354%3Fv%3D2%22%2C%20%22html_url%22%3A%20%22https%3A//github.com/zcwilt%22%7D%7D%5D%2C%20%22title%22%3A%20%22General%20Comment%22%7D%7D%2C%20%22approved%22%3A%20%7B%22https%3A//github.com/zcwilt%22%3A%20%7B%22avatar_url%22%3A%20%22https%3A//avatars.githubusercontent.com/u/227354%3Fv%3D2%22%7D%7D%7D'></a>
<a href='https://www.codereviewhub.com/'><img src='http://www.codereviewhub.com/site/github-bar.png' height=40></a>

<img src='http://www.codereviewhub.com/site/github-approved-avatar.png'><a href='https://github.com/zcwilt'><img src='https://avatars.githubusercontent.com/u/227354?v=2' width=34 height=34></a>

<a href='https://www.codereviewhub.com/zencart/zc-v1-series/pull/159?approve=1'><img src='http://www.codereviewhub.com/site/github-approve.png' height=26></a>&nbsp;<a href='https://www.codereviewhub.com/zencart/zc-v1-series/pull/159?approve=0'><img src='http://www.codereviewhub.com/site/github-undo-approve.png' height=26></a>&nbsp;<a href='https://github.com/zencart/zc-v1-series/pull/159'><img src='http://www.codereviewhub.com/site/github-refresh.png' height=26></a>
<a href='#crh-end'></a>