Feature - Adding Dataframe applicability to some Series string methods
Hello,
Initially the string methods, like replace, lower, zfill, strip etc etc.. are restricted to Series use only.
It would be good if a parameter is put to use it on data frames too. Methods like strip won't affect numeric columns since they wount be having spaces already. But if there is a method which can affect a numeric column, it can be excluded using exclude parameter (which should be added). 
A simple way of doing it is demonstrated below. 

```
import pandas as pd
data=pd.read_csv("nba.csv")
data
dtypes=data.dtypes.astype(str)
for columns in data.columns:
    data[columns]=data[columns].astype(str)
    data[columns]=data[columns].str.replace(" ","")
    data[columns]=data[columns].astype(dtypes[columns])
data
```
In this example, the method is working fine with Series of all dtypes. And after successfully applying method, the columns are converted back to their original dtype.

If this issue is approved, I would like to work and contribute to this feature.