WINDUP-156: Some simplifications to Iteration variable handling (implici...

...t iteration variable names)

## How it works after this?
Now, you are able to name only the variables you are going to use, otherwise they are going to be calculated using defaults. You have 4 options to write rules.

* The old one, specify everything: 
```java
.when(
Query.find(AbcModel.class).as("abcModels")
).perform(
 Iteration.over("abcModels").as("abcModel")
....
```
* Specify **only** the list **iterable** name. When this is used, the name for each iterated variable is calculated automatically in the Iteration class (there is a specific method that returns for the given list it's calculated name). Right now it adds suffix "_instance"
```java
Query.find(AbcModel.class).as("abcModels")
).perform(
 Iteration.over("abcModels")
...
```
* Iterate over the variable set having the given types inside
```java
Query.find(AbcModel.class).and(Query.find(SecondModel.class))
).perform(
 Iteration.over(AbcModel.class)
...
```


* Specify **nothing**, everything is called using the default names saved as the static finals in the Iterator. 
```java
Query.find(AbcModel.class)
).perform(
 Iteration.over()
....
```
## Rewriting the rules
I have rewritten all the rules. The **old style** is used only for the reporting rules that are using the variable name in the reports. The **3. style** is used everywhere it looked it fits. Otherwise, the **2. style** is used.
If this PR will be accepted, I will update our wiki also with this message.

## Tests
`mvn clean install` passed on this PR.

## Future simplification
I would like to rename Iteration -> ForEach, over() -> in(). Foreach.in("...") would made it clearer for the rules I came across, however didn't came across all the rules (it may not fit to some rules). What do you think?
It is relevant only to the second usage of the rule writing, when you specify only the list (list from varstack that you want to iterate over) but do not specify the name of each of the variable from this list. Right now it generates that name using list_name + "_instance". We are discussing if just "it" (inspired by groovy) wouldn't be enough. This single variable name can used for example in reporting (goo.gl/2x2fcR using sourceReport -- in this case the rule specified the name, so the "it" would not be used) or in the perform when accessing that variable can be needed (goo.gl/pXAJdo -- this is example from this PR, not in master yet. It uses the method Iteration.singleVariableIterationName("javaMethods") because in the iteration, a single name was not selected and therefore it was calculated. Here comes the discussion, if this shouldn't be just "it").