adjust mockery minimum version again for phpunit

and php 5.6 build success. Maybe I read the sources correct this time.
refs #30

reordered the composer-flags env variable string to better see what is
being used as dependencies in the travisci UI. refs #30

.travis.yml

@@ -4,19 +4,19 @@ matrix:
   fast_finish: true
   include:
     - php: 5.6
-      env: COMPOSER_FLAGS="update --prefer-source --prefer-lowest --prefer-stable"
+      env: COMPOSER_FLAGS="update --prefer-lowest --prefer-stable --prefer-source"
     - php: 7.0
-      env: COMPOSER_FLAGS="update --prefer-source --prefer-stable"
+      env: COMPOSER_FLAGS="update --prefer-stable --prefer-source"
     - php: 7.1
       env: COMPOSER_FLAGS="install"
     - php: 7.1
-      env: COMPOSER_FLAGS="update --prefer-source --prefer-stable"
+      env: COMPOSER_FLAGS="update --prefer-stable --prefer-source"
     - php: 7.2
       env: COMPOSER_FLAGS="install"
     - php: 7.2
-      env: COMPOSER_FLAGS="update --prefer-source --prefer-stable"
+      env: COMPOSER_FLAGS="update --prefer-stable --prefer-source"
     - php: 7.2
-      env: COMPOSER_FLAGS="update --prefer-source --prefer-lowest --prefer-stable"
+      env: COMPOSER_FLAGS="update --prefer-lowest --prefer-stable --prefer-source"
   allow_failures:
     - php: nightly
 

composer.json

@@ -51,7 +51,7 @@
         "phpunit/phpunit": "^5.4 || ^6.0",
         "phpmd/phpmd": "^2.6",
         "squizlabs/php_codesniffer": "^2.8 || ^3.0",
-        "mockery/mockery": "^0.9 || ^1.0"
+        "mockery/mockery": "^0.9.9 || ^1.0"
     },
     "autoload": {
         "psr-4": { "Trellis\\": "src/" }