Fix OS_NAME

So that it works on both linux and osx

Author: BanzaiMan

.travis.yml

@@ -51,7 +51,7 @@ install:
 before_script:
 - 'export INSTALL_DEST=${INSTALL_DEST:-/opt/python}'
 - export LSB_RELEASE=$(lsb_release -rs 2>/dev/null || sw_vers -productVersion | sed 's/^\([0-9][0-9]*.[0-9][0-9]*\).*/\1/')
-- 'export OS_NAME=${OS_NAME:-$(lsb_release -is 2>/dev/null | tr "A-Z" "a-z" || echo "osx" | tr "A-Z" "a-z")}'
+- 'export OS_NAME=$((lsb_release -is 2>/dev/null || echo "osx") | tr [[:upper:]] [[:lower:]])'
 - 'export ARCH=${ARCH:-$(uname -m)}'
 - 'export PACKAGES=${PACKAGES:-pip nose pytest mock wheel}'
 - 'export CPYTHON_ONLY_PKGS="numpy"'