Fix overlay not full screen in some devices (Issue 114)

[jackyhieu1211-hn]

Fix overlay not full screen in some devices (Issue 114) https://github.com/worker8/TourGuide/issues/114

[carlos-mg89]

@hieuseesaa thanks for the PR, it works fine!

@worker8 I've tested this pull request by changing the dependency import in my Gradle and it works like a charm:

implementation "com.github.hieuseesaa:tourguide:b00064a"

Could you please accept this PR and make another release? Alternatively, if you add me as maintainer of this library, I could do this for you as well. I could commit to this library.

Thanks in advance!