MINOR: fix Email class modifying SSViewer.source_file_comments config val

The Email class was updating the SSViewer.source_file_comments value and not
resetting it. If someone had this value set to true in their system and then
used the Email class, it seems there would be an unintended side-effect of
having the source file comments turned off.
Docs: Note about branch merging
BUG Fixed issue where time value was being parsed incorrectly in some locales
Fixed HTMLEditorField extension call ("updateFieldsForOembed")
BUG Fixed missing allowed_actions on UploadField_SelectHandler
Fixed broken github issue tracker link
Postgres compat in SQLQueryTest
Postgres compat in MemberCsvBulkLoaderTest and GroupTest
PHP 5.5 CI, don't allow failures for sqlite3 and postgres
Merge pull request #2196 from chillu/pulls/travis-matrix

PHP 5.5 CI, don't allow failures for sqlite3 and postgres
Use preg_replace_callback over preg_replace with e modifier
API HTTP::urlRewriter with (string)$code deprecated in 3.1. Fixed regressions and CSS urls.

urlRewriter will expect a callable as a second parameter,
but will work with the current api and simply raise a deprecation error.

HTTP::absoluteURLs now correctly rewrites urls into absolute urls. Resolves introduced in c56a80d6ce

HTTP::absoluteURLs now handles additional cases where urls were not translated.

Test cases for HTTP::absoluteURLs added for both css and attribute links.

Cleaned up replacement expression and improved documentation.
Removes PHP 5.5 from allowed failures
Merge pull request #2192 from dangerdan/patch-1

Fixed broken github issue tracker link
Merge pull request #2182 from hafriedlander/fix/sanitise

FIX HtmlEditorField not re-checking sanitisation server side
FIX Recent patch to DataObject#db changed API which broke core
Merge branch '3.0' into 3.1

Conflicts:
	.travis.yml
	control/HTTP.php
	email/Mailer.php
	tests/control/HTTPTest.php
Merge pull request #2197 from hafriedlander/fix/dbapichange

FIX Recent patch to DataObject#db changed API which broke core
Quote table/column names when falling back to $fullName
Merge pull request #2198 from simonwelsh/pgtest

Quote table/column names when falling back to $fullName