Merge pull request #198 from bhariharan/master

Mobile SDK 2.3.0 Release
Merging back from 'master' to unstable
Merge pull request #200 from bhariharan/unstable

Merging back from 'master' to unstable
Better log level control in smartstore plugin
Log level control for smart sync
Updated split files
Posting 2.3 version of the Dev Guide.
Merge pull request #202 from rwhitley/master

Posting 2.3 version of the Dev Guide.
Log level can be specified in uppercase
Merge pull request #201 from wmathurin/unstable

Better log level control in smartstore plugin and smartsync
Merge branch 'master' into unstable
Merge pull request #203 from bhariharan/unstable

Merge 'master' to unstable
timing all cordova.exec calls leveraging console.time and console.timeEnd
More timing in smartsync/forcetk - could be refined some more e.g. we might want to turn it on/off like we do other log ging
Merge pull request #204 from wmathurin/unstable

Some timing for cordova calls / smartsync and forcetk
More timing logged
Merge from upstream
Merge branch 'unstable' of github.com:forcedotcom/SalesforceMobileSDK-Shared into unstable
Adding hybrid tests for concurrent upserts
Merge branch 'hybrid_upsert_tests' into hybrid_concurrent_upsert_tests
Merge pull request #205 from khawkins/hybrid_concurrent_upsert_tests

Tests to exercise concurrent upserts on the same data from hybrid