Merge pull request #348 from SC5/dev

Updating master from dev for 0.2.15
Minor fixes to releasing instruction
Merge pull request #349 from varya/features/fix-instruction

Minor fixes to releasing instruction
Disable save button if no dirty variables are found
Send only dirty variables from client to server when saving
Split variable writing to its own module
Merge pull request #355 from jpbackman/save-only-changed-variables

Save only changed variables