Fix various glitches in WeaponStatsAdapter

Fixed issue where app crashes due to division by zero (caused by time equipped < 60)
Fixed issue where views would incorrectly be displayed due to recycling
Fixed issue where KPM calculation would be off, now using Battlelog way of doing it:

    Example: kills = 100, seconds = 119
    Previously: kills / ((int) (seconds / 60)) => 100
    Now: (kills / (seconds)) * 60 => 50.42

    The reason for the previous calculation to be slightly off is due to the int cut-off (despite
    it being 99.1% of 120)
Address similar issues to 6f4ac33 in VehicleStatsAdapter
Move duplicated functionality into separate class
 • Updated changelog
 • Reworded changelog
Merge pull request #129 from ninetwozero/fix-crashing-on-weapon-stats

Fix crashing on weapon stats