URGENT bugfix

We never cleaned up the mCellData and mWifiData  after reading from them - making them become HUGE and exponentially increasing storage necessary by MozStumbler by having thousands if not millions of duplicates.
Merge pull request #592 from tamcap/bugfix_URGENT

URGENT bugfix,  mCellData and mWifiData not being cleared after reporting the collected locations.
MozStumbler v0.20.2
Merge pull request #594 from garvankeeley/v-0.20.2

MozStumbler v0.20.2
MozStumbler v0.20.3
Merge pull request #595 from garvankeeley/master

MozStumbler v0.20.3