Related: #2067
Ahh, its a pull request not an issue, thought I had seen it. @codebrainz searching wins again.
If we just wanted to bump to a GCC version that actually supports C++11 properly, I think we could just change dist to xenial to get GCC 5.4.
Thats the simple way to at least get C++11.
As the link shows it should be possible to go up to gcc7 with trusty and I suspect up to 8 with xenial. The way the link does it using Travis built in capabilities is neater than #2067 so I would suggest that @andy5995 .