Clean up errno logs and sto* conversions

I learned that we should be using PLOG to log errno strings, and we
should be avoiding stoi, stol, etc... conversions and instead use the
built in Android ParseInt/ParseUint functions.

Bug: 150250606
Bug: 150245058
Test: Manual for CLI tools, VTS for everything else
Change-Id: Icdd8a6af8564d5de3bedd1bc934f7928eb5e66e9