Change log level for missing user properties

[vgaidarji]

Fixes #204

What has been done

• Missing apiKey/user error message log level change from info to error (see de1c3ce)
• Ignored autogenerated project files
• General code clean up (removed semicolons)

How to test

• Set user or key to null in bintray closure:

bintray {
    user = null
    key = null
}

• Execute ./gradlew clean build install bintrayUpload -DdryRun=true command and observe logs

Before the change

:dependencies-overview:build
:dependencies-overview:install
:dependencies-overview:bintrayUpload

BUILD SUCCESSFUL

After the change

:dependencies-overview:build
:dependencies-overview:install
:dependencies-overview:bintrayUpload
Skipping task 'dependencies-overview:bintrayUpload' because user or apiKey is null.

BUILD SUCCESSFUL

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