Dashboard helper rewrite

To be tested in conjunction with opentechinstitute/commotion-dashboard-helper#10

* Updates openwrt config file to include httpclient and nixio-cyassl.
* Upgrades cyassl from version 1.6.5 to 2.8.0 (using makefile and patches from openwrt trunk -- https://dev.openwrt.org/browser/trunk/package/libs/cyassl revs 38609 and 38610, respectively)
* Removes curl, libcurl, and libopenssl

To test:
* Follow test procedures in opentechinstitute/commotion-dashboard-helper#10