Added the option to use custom paths for the platforms, packages, cache and projects directories and added the option to turn on/off telemetry

[ItsMeel]

This PR adds the capacity to use custom paths for the platforms, packages, cache and projects directories by adding a setting for each of them and a setting to enable or disable telemetry which should solve issue #898.

It works by assigning the configuration value of the environment variables:

Configuration	Environment variable	Default value
platformsPATH	PLATFORMIO_PLATFORMS_DIR	null
packagesPATH	PLATFORMIO_PACKAGES_DIR	null
cachePATH	PLATFORMIO_CACHE_DIR	null
projectsDirectoryPATH	PLATFORMIO_SETTING_PROJECTS_DIR	null
enableTelemetry	PLATFORMIO_SETTING_ENABLE_TELEMETRY	true

In the case of the directories if the configuration has some value it will be assigned to the environment variable but if the configuration is null it won't create the environment variable and platformio will use the default directories.

This ability to use custom paths allows the user use a custom platformio installation like installing plaformio in a USB drive and carry all the platforms and toolchains on the go.

Currently there is some obligatory use of the %USER%/.platformio directory for the appstate.json, homestate.json files and .cache/tmp directory but i was able to work from a USB drive without any problem.

[CLAassistant]

All committers have signed the CLA.

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