add an option for have the possibility to avoid the install of the lib

[aiekick]

Hello,

thanks for this great library who is working very well.

btw can you add an option in the CMakeLists.txt for avoid if needed the intallation target.

Im using this lib as a submodule in my project, and im using the install target. but when i install my project, some libs like your is installing not desired many files and directories and so on

thanks for your understanding.

[SpartanJ]

Fixed in PR #117. Thanks to @variar !

[aiekick]

great. thanks