Request to add pycurl details to README

[twhetzel]

I found that pycurl was needed and pip install pycurl was not sufficient. These instructions worked:

• Download the latest version from http://pycurl.sourceforge.net/download/
• Extract the tar.gz that you downloaded
• cd to the extracted directory
• Read the INSTALL file and do what it says

Based on: https://stackoverflow.com/questions/11024051/pycurl-doesnt-import-after-update-python-to-2-7

[rdilts74]

Nice work