.travis.yml: Adapt to latest standard + add variable for JavaVM error

Avoid error:

Error occurred during initialization of VM
Could not allocate metaspace: 1073741824 bytes

trying solution proposed in https://stackoverflow.com/a/33794801

.travis.yml

@@ -17,20 +17,16 @@ python:
 
 env:
   global:
-  - VERSION="12.0" TESTS="0" LINT_CHECK="0" TRANSIFEX="0"
-  - TRANSIFEX_USER='transbot@odoo-community.org'
-  - secure: NUsXwVrMntcqge1ozKW+DSkP7dq+Rla6JVvFF2c89/g+zJaIqQRi8EQBLoqNwCdMk+rjpQeZt/JPELjH+EzPcmGddhDxOgVB3nUT9LvFXGCHF+NjmHXqyba4tuc7BnpG1WDD+rSlxVCt1aIjNIhhaZ4ic0rCWpKNYu/yFTsmChc=
+  - VERSION="12.0" TESTS="0" LINT_CHECK="0" MAKEPOT="0"
+  - WKHTMLTOPDF_VERSION="0.12.4"
   matrix:
   - LINT_CHECK="1"
-  - TRANSIFEX="1"
-  - TESTS="1" ODOO_REPO="OCA/OCB"
-  - TESTS="1" ODOO_REPO="odoo/odoo"
-
+  - MALLOC_ARENA_MAX=4 TESTS="1" ODOO_REPO="OCA/OCB"
+  - MALLOC_ARENA_MAX=4 TESTS="1" ODOO_REPO="odoo/odoo" MAKEPOT="1"
 
 install:
   - git clone --depth=1 https://github.com/OCA/maintainer-quality-tools.git ${HOME}/maintainer-quality-tools
   - export PATH=${HOME}/maintainer-quality-tools/travis:${PATH}
-  - export WKHTMLTOPDF_VERSION=0.12.4
   - travis_install_nightly
 
 script: