Prepare for 3.1.2 release: Link typo in drivers.rst; update frozen modules; fix nRF builds#1404

Merged

kattni merged 3 commits intoadafruit:3.xfrom

dhalbert:drivers.rst-typo

Jan 7, 2019

Commits on Dec 14, 2018

Link typo in drivers.rst
dhalbert
committed

Commits on Jan 6, 2019

update libraries
dhalbert
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use new download location for nRF sd132; remove 52840 boards (they use an alpha sd140 which is no longer available

tannewt
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dhalbert
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