Run tests on PHP 5.6 on travis too
Updated the troubleshooting doc with a chapter for the proc_fork errors that happen on a tiny VPS with no swap space. Also added the solution provided in #1849, #1101, #945.
Merge pull request #2748 from sndpl/issue/1849

Updated the troubleshooting doc with a chapter for the proc_fork errors
Avoid "Package foo/* listed for update is not installed" error

Previously 'compose update foo/*' gave an error
"Package foo/* listed for update is not installed. Ignoring" even if some foo/*
packages were present; however the packages *would* then be updated as
requested. This removes the false error iff foo/SOMEPACKAGE is required.
Merge remote-tracking branch 'parsingphase/avoidFalseWildcardUpdateWarning'
CS fixes, refs #2750