Code cannot be licensed as Apache

[bperrybap]

This code is a derivative of the LiquidCrystal_I2C code which was licensed as LGPL 2.1 so it is subject to the original LGPL 2.1 licensing terms even if it is updated and or enhanced.
Yes, in many cases the actual licensing information was not provided in the LiquidCrystal_I2C source file package but the LiquidCrystal_I2C code is itself a derivative of LiquidCrystal_I2C LGPL 2.1 code so it too is subject to the LGPL 2.1 licensing terms. The original author of the LiquidCrystal_I2C code even stated as much on his web page when he originally released it years ago.
If you need more supporting information on this, I have documentation on the licensing of these files that traces their origins back over 10 years.
Please fix the licensing notices ASAP.
Also, I would recomment that you also create a file called LICENSE or license.txt and put a full textual copy of the LGPL 2.1 license agreemnt.
github uses the licensee script and it will discover this file and post a license notice for the project on the main repository page.

[bperrybap]

See the corresponding licensing issue in upstream repository:
johnrickman#44

[slogan621]

Thanks. I reverted my commit that added Apache2 until I can look more closely into the issue.

[bperrybap]

There isn't much to look at, unless you want to go through the history of the libraries origin.
The LiquidCrystal_I2C code you started with was licensed LGPL 2.1 and since this project is a derivative of that code, it will have conform to that license.

The thing I think is cool is the github use of licensee to autodetect the license and display a "badge" that will show up if you create a file called LICENSE, or license.txt (there are a few other file names) that contains the text of a license. github will use licensee to auto detect the license and put a license icon on the repository and indicate the license type.
You can see what the "badge" looks like on my hd44780 library:
https://github.com/duinoWitchery/hd44780
You can see it on the right hand side just above the "Releases" section.