feat: set limit for num of contacts to select

[lwhiteley]

• create limit params for selecting contacts
• update readme with documentation
• add param to filter contacts without phone numbers

see updated readme: https://github.com/lwhiteley/Android-ContactPicker/

resolves #6

Behaviour Designed:

• A limit parameter was created that defaults to 0
• when greater than zero it will hide the select all button (even if, EXTRA_SHOW_CHECK_ALL is set to true)
• if limit is greater than 0, once you have selected that number of contacts, you cannot select other contacts
• A configurable toast msg will appear when limit has reached and the user tries to select more contacts
• For groups that exceed the limit, this toast will appear,
• For groups that are under the limit, but are selected in combination with others that accumulate over the limit, a toast will appear and selection disabled as well. Eg. below shows a limit of 6 and a user trying to select two groups that exceed the limit

[1gravity]

Thank you! This is a great contribution.

[lwhiteley]

sweet! let me know when a new version is published

[1gravity]

It has been published but it usually takes a while to show in the repository