Improvement to UserStream and ImageUploader class

* Rename QMLUploader to ImageUploader
* UserStream and ImageUploader now use QNetworkAccessManager from
QDeclarativeEngine
* Remove UserStream.status and replace with UserStream.connected
Fix some bugs in displaying rich text
Minor improvement in QML

* Disable loading of thumbnails when the app is in offline mode
* Show loading indicator when loading DM conversation from WorkerScript
in DMThreadPage
Improvement in TweetListView and UserStream.js

* Improve algorithm of parsing user stream response
* Remove TweetListView.parseData() and replace with a few other
functions
Move to Twitter API 1.1

* Minimum auto refresh frequency increase to 5 mins
Fix a bug that cause Qt Linguist lupdate to fail working
Resolve t.co url for user
Update translations files

11 complete and 7 incomplete translation languages
Bump version to 1.8.0 for release
Symbian: Fix a stupid bug
Remove the remove saved search long press dialog in TrendsPage
Harmattan: add postrm to remove database & thumbnails after uninstalled
Made some English language improvements.
Fix some bugs in DM

* DirectMessage.insertDM() function use "newer" type instead of using
reloadType, which may not be "newer"
* When a DM delete response received from streaming, it will be remove
from DMThreadPage as well
* When new DM received and in DMThreadPage, that thread will not marked
as unread
* Correct some spelling error in UserStream.js
Coding improvement

* Cache.qml: Add/improve storeHashtags() and storeScreenNames()
functions
* DirectMessge.qml & TweetListView.qml: Improve refresh() and
onParseComplete() functions
* NearbyTweetsPage.qml, TweetSearchColumn.qml & UserSearchColumn.qml:
Improve refresh() functions
Merge pull request #7 from hugovk/master

Made some English language improvements
Merge branch 'master' of https://github.com/dicksonleong/Tweetian
Fix non-ASCII hashtags are not linked in rich text

Use a new algorithm which use indices to replace the hashtags
Fix last update for DM is not updated after refresh
Remove pull down to refresh gesture in UserCategoryPage