Merge pull request #2 from keestux/master

Remove reference to SoftI2CMaster in the README
Added conductivity measurement

Added (calibrated) conductivity measurement. Also added 2 lines of code
that will reduce the I2C clock speed so long range communication is
possible.
Update README.md
Update README.md
Update README.md
Move EC_ADDR macro to ECMeter.cpp

And also the Wire.h include is moved to ECMeter.cpp
Testing SourceTree
Removed text files from sourcetree test
Merge remote-tracking branch 'nickl/master'

Conflicts:
	ECMeter.cpp (extra function was added by Nick)