[libsocialcache] Avoid recreating delegates on model updates.
[libsocialcache] Cache prepared queries.
Merge pull request #16 from adenexter/master

Improve model performance
Bump version
[bugfix] Fixed an issue that generated potential wrong SQL queries

This commit prevents the other keys to be empty during an
UPDATE query.
[feature] Small API change for image downloader

This commit changes the signature of a signal to
transmit the data that were used to download
a specific image.
Merge pull request #17 from SfietKonstantin/sqlbugfix

[bugfix] Fixed an issue that generated potential wrong SQL queries
Merge pull request #18 from SfietKonstantin/dl-api

[feature] Small API change for image downloader
[feature] Enhancements to contacts database

This commit adds some missing methods to the
contacts database, like contacts removal
and cached image management.