WIP: Create Hologram Publisher

[dnowacki-usgs]

This is code I wrote many months ago, recently updated to be mostly consistent with modern ModularSensors code formatting, that implements a publisher that uses the Hologram socket API. It is based off of EnviroDIYPublisher.cpp/EnviroDIYPublisher.h. There are a number of rough edges. In particular, the Hologram Device ID is currently hard-coded in HologramPublisher.cpp, and should really be set externally...I am not at all a C++ programmer. Would love input or modifications; I'm just putting this up here since there has been interest, particularly in #305.

[aufdenkampe]

@SRGDamia1, should we point this PR to develop, or merge directly into master?

Also, I haven't tested this on my own hardware. @dnowacki-usgs provides extra details on how to configure things in #305, so I might be able to try testing in over the next few weeks, but not right away.

[dnowacki-usgs]

Hi @aufdenkampe thanks for the edits! I haven't had a chance to test them but they look good to me. I mentioned this (by linking to a gist) in #305, but this is how I generate the HologramAPI publisher in the logger .ino file:

const char *registrationToken = "xxxxxxxx";   // Make this the Hologram Device Key
const char *samplingFeature = "12345678-abcd-1234-ef00-1234567890ab";     // Sampling feature UUID

// Publisher for Hologram
// Create a data publisher for the EnviroDIY/WikiWatershed POST endpoint
#include <publishers/HologramPublisher.h>
HologramPublisher HologramAPI(dataLogger, &modem.gsmClient, registrationToken, samplingFeature);

Note that samplingFeature remains from the MMW code I based this off of, although it is unused, and the variable registrationToken might be better renamed deviceKey or something.

[aufdenkampe]

@SRGDamia1, it's been a while since we actively discussed this, and the APIs have likely changed, but the benefits described in the following issue could still prove to be quite beneficial to our server-side bottlenecks at Model My Watershed.

Here's the relevant issue thread, with the reasoning why this feature could be useful.

• Develop publisher to Hologram.io Data Router #305