[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.
Merge pull request #19 from SfietKonstantin/contacts-enhancement

Contacts enhancement
[bugfix] Fixed an issue in updating contact entry

This commit fixes an issue where updating a contact
entry might reset other entries.
Merge pull request #20 from SfietKonstantin/master

[bugfix] Fixed an issue in updating contact entry
Bump version
[feature] Extended image downloader

This commit ads a nicer API for image downloader,
making it easy to customize requests, like signed
requests.
[feature] Be able to store Facebook media URL

This commit provides the capability to cache Facebook
media URL, and expose it in the model.
Merge pull request #21 from SfietKonstantin/abstract-image-downloader

[feature] Extended image downloader
Merge pull request #22 from SfietKonstantin/url

Store media url
[bugfix] Makes libsocialcache to build

This commit fixes a warning in abstract image
downloader, and also makes libsocialcache build
again, by removing a deprecated moc include.
Merge pull request #23 from SfietKonstantin/bugfix

[bugfix] Makes libsocialcache to build
Bump version
Added modelUpdated signal to QML models
Merge pull request #24 from antseppa/master

Added modelUpdated signal to QML models
Bump version
[libsocialcache] Optimize image downloading.