Bump project version when version is stored in VERSION

bump.sh

is-executable() {
    local BIN=`command -v "$1" 2>/dev/null`
    if [[ ! $BIN == "" && -x $BIN ]]; then
        return 0
    else
        return 1
    fi
}

# a wrapper for versionbump
# https://github.com/vortec/versionbump
# defaults to patch
# assumes a VERSION file exists only containing current version
# $1 - place to bump
function bump () {
    if is-executable versionbump; then
        if [ -z "$1" ]; then
            version_place='patch'
        else
            version_place=$1
        fi

        current_version=`cat VERSION`
        `versionbump -c $current_version $version_place VERSION` 2> /dev/null
        return 0
    else
        echo "versionbump not installed, install by running 'pip install versionbump'"
        return 1
    fi
}