detect file infomation more accurately
eliminate some static analyis warnings

** CID 73898:  Resource leak in object  (CTOR_DTOR_LEAK)
/src/filebrowser/data-cache.cpp: 24 in DirentsCache::DirentsCache()()

** CID 73903:  Uninitialized pointer field  (UNINIT_CTOR)
/src/filebrowser/data-cache.cpp: 57 in FileCacheDB::FileCacheDB()()

** CID 73898:  Resource leak in object  (CTOR_DTOR_LEAK)
/src/filebrowser/data-cache.cpp: 57 in FileCacheDB::FileCacheDB()()
add some actions for context menu
if cancelled, don't continue to do the rename task
rename RenameDirent* to RenameFolder* and trim the input of new_name
Merge pull request #269 from haiwen/bugfix-6

eliminate some static analyis warnings
refine the words of confirmation

discussion: https://github.com/haiwen/seafile-client/pull/258#discussion_r19922023
move the getBrand to utils/utils.cpp and remove duplicated defaultCcnetDir
Merge pull request #276 from haiwen/patch-19

move the getBrand to utils/utils.cpp and remove duplicated defaultCcnetDir
Merge pull request #258 from Chilledheart/patch-14

add a right click menu for item
update file browser
collaspe rename* and remove* into renameDirent and removeDirent respectively
fix a memory usage issue
expire the dirents_cache correctly and fix a bug discussed before

see more https://github.com/haiwen/seafile-client/pull/258#discussion_r19922864
Merge pull request #278 from Chilledheart/develop

expire the dirents_cache correctly and fix a bug discussed before
Merge pull request #279 from haiwen/bugfix-memory-usage

fix a memory usage issue
Merge pull request #256 from haiwen/patch-13

detect file infomation more accurately
current file exists. overwrite it, or upload as an alternative name