Ubuntu: Add licence header to HeaderComponent.qml

REVIEW: 118430
BUG: 335597
Do not call that function when setting up signals & slots

CCMAIL: dpniel@ubuntu.com
Reset auto-reconnect cycle when user explicitly changes network preference

Previously, a network error message box would be deleted and reinitialised
only when Trojita got a working connection to the server after a cycle
of reconnect attempts.

Now, whenever the user changes the network preferences, the
Imap::Model::NetworkWatcher apart from resetting the timeouts also emits a
signal that triggers deletion and reinitialisation of the error message
box at the GUI layer. This allows Trojita to treat a user's manual attempt
to re-connect as a new try-fail-reconnect cycle and throws a message pop-
up on a network error (even if the error string hasn't changed since last
time).

Use-Case: Error in network; Trojita shows an error message and starts a
series of auto reconnect attempts. User wishes to stop the attempts and
chooses "Offline" from the Network Access menu item. Attempts stop. After
a while, user wishes to try connecting again and chooses "Free Access".
If attempt to connect terminates in a network error, Trojita throws a
fresh new error message and starts a new auto-reconnect cycle (even if the
error string is the same as what it before the explicit switch to "offline").

REVIEW: 118434
Ubuntu:Add Click pkg manifests and change cmake to build click pkgs

REVIEW: 118429
Ubuntu: Remove QCommandLineParser options from src/Ubuntu/main.cpp

For some reason UbuntuTouch/Unity8 require --desktop_file_hint
and --stage_hint to be passed when launching an app. Which
the commandline parser was blocking these args. Since the
commandline options were only really just setting the size of
the qquickview we can safely just remove it and stick to a fixed
size window.

Removed associated context properties from main.qml

REVIEW: 118429