CI/CD: add new distros, remove EOL distros

CestOS 6, Ubuntu Trusty, Debian Wheezy do not have the
libmosquitto-{devel,dev} package, so omitted.

Part of #19.
Fixes #27.

Author: Totktonada

.travis.yml

@@ -11,32 +11,16 @@ env:
     global:
       - PRODUCT=tarantool-mqtt
     matrix:
-#      - OS=el DIST=6
       - OS=el DIST=7
-      - OS=fedora DIST=24
-      - OS=fedora DIST=25
-#      - OS=ubuntu DIST=precise
-#      - OS=ubuntu DIST=trusty
+      - OS=fedora DIST=26
+      - OS=fedora DIST=27
       - OS=ubuntu DIST=xenial
-      - OS=ubuntu DIST=yakkety
-#      - OS=debian DIST=wheezy
+      - OS=ubuntu DIST=artful
+      - OS=ubuntu DIST=bionic
+      - OS=ubuntu DIST=cosmic
       - OS=debian DIST=jessie
       - OS=debian DIST=stretch
 
-#matrix:
-#    allow_failures:
-#      - env: OS=el DIST=6
-#      - env: OS=el DIST=7
-#      - env: OS=fedora DIST=24
-#      - env: OS=fedora DIST=25
-#      - env: OS=ubuntu DIST=precise
-#      - env: OS=ubuntu DIST=trusty
-#      - env: OS=ubuntu DIST=xenial
-#      - env: OS=ubuntu DIST=yakkety
-#      - env: OS=debian DIST=wheezy
-#      - env: OS=debian DIST=jessie
-#      - env: OS=debian DIST=stretch
-
 script:
   - git describe --long
   - git clone https://github.com/packpack/packpack.git packpack