tools: install components optionally

Pull Request check-list

• Does make -j8 test (UNIX) or vcbuild test nosign (Windows) pass with this change (including linting)?
• Is the commit message formatted according to CONTRIBUTING.md?

Affected core subsystem(s)

tools

Description of change

Refer: https://github.com/nodejs/node/pull/5734

This introduces a command line option, ('-c' or '--components') to install components optionally. The valid components are

• node
• npm
• headers

All these components can be installed or uninstalled, like this

python tools/install.py -c node,headers install . /

python tools/install.py --components npm uninstall . /

"-c" is just the short form of "--components"

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cc @rvagg @bnoordhuis