Added working version of exchange-sdk upgrade to release to maven-central.
Added /target to ignore.
Updated topmost gitignore. Removed gitignore from engine.
Merged changes from dev. Removed jar files before release.
Updated Maven repository from test to prod.
Updated README. Updates #26.

Added details on Exchange SDK Maven availability.
Incremented version for next iteration 0.11.1 -> 0.11.2-SNAPSHOT. Updated javadoc.
Set SDK dependency version to 0.11.2-SNAPSHOT. Updated exchange demo with image attaching functionality.
Updated exchange tests to use current dev SDK version 0.11.2-SNAPSHOT.
Merge branch 'dev' into maven_central
Merge pull request #41 from OfficeDev/maven_central

Merged latest changes as committed to Maven Central. Incremented Exchange SDK version for new iteration (0.11.2-SNAPSHOT). Updated Exchange samples and e2e tests accordingly.
Added support for attaching images to emails for the Exchange demo. Fixes #42.
Updated POM to make it dependent on MC artifact.
Removed jar file from libs/.
Removed machine dependent generated files.
Removed machine dependent generated files.
Updated SDK behavior to report an error if server error occurred during InvocationHandler (except for 404). Removed javadoc jar since it is available via Maven.
Reverted classpath deletion to simplify setup. This is temporary action until instruction are updated.
Removed .classpath. Updated pom.xml to consume Android standard sources structure. Changed sources structure (removed main/java layer).
Added inheritance of complex types. Fixed date parsing after Server change.
Added logic to attach images to events. Refactored classes structure (WIP). Updates #12.
Used appropriate constant for notification message.
updating lists API to guava Future implementation