Filesystems and data partitions (SD/SPIFFS/LittleFS/SD_MMC) (#92)

* @tuan-karma's compiler warning fix (#a0e9e5c)
* LittleFS/SD/SD_MMC/SPIFFS (any FS) support for certs/signatures
* Auto assign filesystem when applicable
* Added SPIFFS/LittleFS partition support to execOTA()
* Added Callback setter for Update progress handler
* Implemented `esp32fota.setExtraHTTPHeader( name, value )`
* C++11 compliance
* Credits update
* Updated examples
* Created test suite (#6) 
* Added Dispatchable Workflow for library maintainers (manual triggering)
* bump version

Bump version

Update library.properties

Update library.json

Getting ready for 0.1.4

Update library.properties

New release version

Fixed error with checkURL

Updated Readme