Release 1.6.0

[dmitrykuzmin]

This PR does the release of a library version 1.6.0.

This release brings API and infrastructure updates to the framework.

API changes

1. The JS Client now supports multitenancy [Multitenancy support #141].

   The Client factory API now accepts a TenantProvider as an element of the passed client options.

   The TenantProvider defines the current tenant ID to be used for all requests done with the client. 
The current tenant ID can be dynamically updated with the help of TenantProvider.update(tenantId). For single-tenant applications, the TenantProvider can be omitted in the options.


   Multitenant client usage example:


let tenantProvider = new TenantProvider(initialTenantId());

let client = spineWeb.init({
		protoIndexFiles: [protoIndex],
 		endpointUrl: endpointUrl,
 		firebaseDatabase: firebaseDatabase,
  		actorProvider: new ActorProvider(),
  		tenantProvider: tenantProvider
	});

// …
tenantProvider.update(newTenantId());

2. The FirebaseCredentials are now constructed from GoogleCrendetials rather than the deprecated GoogleCredential. The factory method accepting GoogleCredential is deprecated [Allow to create FirebaseCredentials from GoogleCredentials #137].

3. The onRejection callback of CommandRequest is renamed to onImmediateRejection to better reflect its purpose [Clarify the command request rejection callback API #151]. See also the corresponding changes in core-java.

Infrastructure

1. The JS client docs are now published to spine.io [Publish JS docs to spine.io #136].
2. The project build scripts are migrated to Kotlin [Kotlin Gradle scripts #142].

[codecov]

Codecov Report

Merging #152 into master will not change coverage.
The diff coverage is n/a.

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  Coverage     61.79%   61.79%           
  Complexity      178      178           
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  Files            88       88           
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  Branches         40       40           
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  Hits           1352     1352           
  Misses          827      827           
  Partials          9        9