Remove paths from for_app invocations in rules

I presume that the `./` in `./gradlew` was used here because thefuck
would not find an app match on just `gradlew`, and thus no fucks would
be given on the most common and idiomatic way of invoking gradlew.

After 8faf9b1, thefuck does not distinguish between commands with
paths and those without. Therefore, the tests for this rule are now
broken because thefuck strips paths from the _user_'s command, but not
from the for_app decoration.

This commit addresses that problem by changing the for_app decoration to
this rule.

Author: Ryan Delaney

thefuck/rules/gradle_no_task.py

@@ -5,7 +5,7 @@
 regex = re.compile(r"Task '(.*)' (is ambiguous|not found)")
 
 
-@for_app('gradle', './gradlew')
+@for_app('gradle', 'gradlew')
 def match(command):
     return regex.findall(command.output)