docs(codingstyle): update min qt version

.travis/build-ubuntu-14-04.sh

@@ -19,7 +19,7 @@
 # stop as soon as one of steps will fail
 set -e -o pipefail
 
-# Qt 5.3, since that's the lowest supported version
+# Qt 5.5, since that's the lowest supported version
 sudo add-apt-repository -y ppa:beineri/opt-qt551-trusty
 sudo apt-get update -qq
 

doc/coding_standards.md

@@ -25,9 +25,9 @@ imposed:
 ### Compatibility
 
 qTox is linked against Qt 5, allowing the use of Qt constructs and library
-features. The current minimum supported Qt version is Qt 5.3, meaning that all
-code must compile in a Qt 5.3 environment. Any usage post-Qt 5.3 features must
-be optional and be disabled when compiling/running in a Qt 5.3 environment.
+features. The current minimum supported Qt version is Qt 5.5, meaning that all
+code must compile in a Qt 5.5 environment. Any usage post-Qt 5.5 features must
+be optional and be disabled when compiling/running in a Qt 5.5 environment.
 
 ### No Exceptions