bem make should fail if dependency in deps.js not met

[hsalkaline]

bem -v 0.6.8

steps to reproduce:

get project-stub

make content of below files as described

desktop.bundles/index/index.bemjson.js:

({
    block: 'b-page',
    content:[
        {
            block: 'block'
        }
    ]
})

desktop.blocks/block/deps/js:

({
    mustDeps: [
        { block: 'another-block' }
    ]
})

another-block is not present in project

run bem make

expected behavior

build should fail (or at least produce warning) with message of unmet dependency "another-block" for block "block"

actual result

build finishes without errors

[arikon]

@hsalkaline Should we do it for mustDeps only? Could you make PR for the support/0.6.x branch, please?