Add FAQ entry on how to deal with a very long "allowed_domains"

[redapple]

See #1908 (comment)

[kriti21]

May I take this?

[redapple]

@kriti21 , sure! Thanks for jumping in

[kriti21]

I am not sure if this is the right place to ask this but I am stuck on installing re2 on my system ( Ubuntu 15.10). I have installed all the prerequisites. After that if I run sudo easy_install re2 , I get

Couldn't find a setup script in /home/kriti/re2

and using pip this

error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
Command "/home/kriti/venv/bin/python2 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-5yF05T/re2/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-vRBSAS-record/install-record.txt --single-version-externally-managed --compile --install-headers /home/kriti/venv/include/site/python2.7/re2" failed with error code 1 in /tmp/pip-build-5yF05T/re2/

I have tried every solution I could get online and yet this is not getting resolved. Please help