Fix up CI toolchain - CakeBuild, CakeBuildTools, and AppVeyor

[SubPointSupport]

Currently, SPMeta2 uses several moving parts for CI:

• CakeBuild - a C# build system on top of Roslyn
• CakeBuildTools - a wrapper on top of CakeBuild
• AppVeyor - a CI server

The problem occurs with CakeBuild/CakeBuildTools versioning. Major or minor tool upgrades within CakeBuild leads to CI failures. Current scripts cannot restore and find needed packages, hence CI fails. The following needs to be done:

• [x] Versioning lock within CakeBuildTools dependencies
• [x] CakeBuildTools clean up - remove github, octokit, Wyam and all other non-CI related things (they will be moved into separate documentation stream)
• [x] Setup daily trigger (AWS Lambda / Azure Function) for nighly CI runs

The goal is to stabilize CI workflow used for SPMeta2 build ensuring that it can be built at any point in time. Nightly build on a trigger will also ensure the stability of the CI failing the build early.

[SubPointSupport]

Initial testing with hourly dev builds on AppVeyor looks good. We put together AWS Lambda / Azure Function with hourly / daily schedule to trigger and manager various builds: time, parameters, and configurations.

Will be tuning moving it to daily one but overall ticket is closed. CI is run on schedule the way we want, so no more deviations is expected.

https://ci.appveyor.com/project/SubPointSupport/spmeta2/history